[Fix] Duplicate fields.

Newer versions of hugo will error and fail when the .md files have
duplicated fields, e.g. :

  $ ./hugo-server.sh
  Start building sites …
  hugo v0.152.1+extended+withdeploy darwin/arm64 BuildDate=2025-10-22T19:10:44Z VendorInfo=brew

  Total in 2716 ms
  Error: error building site: process: readAndProcessContent: ".../content/learning-paths/cross-platform/dynamic-memory-allocator/_index.md:57:1": [56:1] mapping key "layout" already defined at [7:1]
    53 | ### FIXED, DO NOT MODIFY
    54 | # ================================================================================
    55 | weight: 1                       # _index.md always has weight of 1 to order correctly
  > 56 | layout: "learningpathall"       # All files under learning paths have this same wrapper
         ^
    57 | learning_path_main_page: "yes"  # This should be surfaced when looking for related content. Only set for _index.md of learning path content.
    58 |

This commit removes the duplicates, keeping the most "rich" version of
the field (the one that has a comment) and prefering the field in the
'FIXED, DO NOT MODIFY' section.

Author: Arnaud-de-Grandmaison-ARM

content/learning-paths/cross-platform/dynamic-memory-allocator/_index.md

@@ -5,7 +5,6 @@ minutes_to_complete: 120
 
 who_is_this_for: This is an introductory topic for software developers learning about dynamic memory allocation for the first time, and who may have used malloc and free in C programming. It also provides a starting point to explore more advanced memory allocation topics.
 
-layout: learningpathall
 learning_objectives:
 - Explain how dynamic memory allocation and the C heap works
 - Write a simple dynamic memory allocator
@@ -56,4 +55,4 @@ shared_between:
 weight: 1                       # _index.md always has weight of 1 to order correctly
 layout: "learningpathall"       # All files under learning paths have this same wrapper
 learning_path_main_page: "yes"  # This should be surfaced when looking for related content. Only set for _index.md of learning path content.
----
+---

content/learning-paths/embedded-and-microcontrollers/tfm/_index.md

@@ -58,6 +58,5 @@ further_reading:
 weight: 1                       # _index.md always has weight of 1 to order correctly
 layout: "learningpathall"       # All files under learning paths have this same wrapper
 learning_path_main_page: "yes"  # This should be surfaced when looking for related content. Only set for _index.md of learning path content.
-layout: learningpathall
 
 ---

content/learning-paths/embedded-and-microcontrollers/zephyr/_index.md

@@ -53,6 +53,5 @@ further_reading:
 weight: 1                       # _index.md always has weight of 1 to order correctly
 layout: "learningpathall"       # All files under learning paths have this same wrapper
 learning_path_main_page: "yes"  # This should be surfaced when looking for related content. Only set for _index.md of learning path content.
-layout: learningpathall
 
 ---

content/learning-paths/servers-and-cloud-computing/bitmap_scan_sve2/_index.md

@@ -46,5 +46,4 @@ further_reading:
 weight: 1                       # _index.md always has weight of 1 to order correctly
 layout: "learningpathall"       # All files under learning paths have this same wrapper
 learning_path_main_page: "yes"  # This should be surfaced when looking for related content. Only set for _index.md of learning path content.
-layout: learningpathall
 ---

content/learning-paths/servers-and-cloud-computing/codec/_index.md

@@ -56,5 +56,4 @@ further_reading:
 weight: 1                       # _index.md always has weight of 1 to order correctly
 layout: "learningpathall"       # All files under learning paths have this same wrapper
 learning_path_main_page: "yes"  # This should be surfaced when looking for related content. Only set for _index.md of learning path content.
-layout: learningpathall
 ---

content/learning-paths/servers-and-cloud-computing/flink/_index.md

@@ -23,9 +23,7 @@ cloud_service_providers: AWS
 armips:
 - Neoverse
 
-layout: learningpathall
 
-learning_path_main_page: 'yes'
 
 operatingsystems:
 - Linux

content/learning-paths/servers-and-cloud-computing/glibc-with-lse/_index.md

@@ -23,9 +23,7 @@ subjects: Performance and Architecture
 armips:
 - Neoverse
 
-layout: learningpathall
 
-learning_path_main_page: 'yes'
 
 operatingsystems:
 - Linux

content/learning-paths/servers-and-cloud-computing/memcached/_index.md

@@ -47,5 +47,4 @@ further_reading:
 weight: 1                       # _index.md always has weight of 1 to order correctly
 layout: "learningpathall"       # All files under learning paths have this same wrapper
 learning_path_main_page: "yes"  # This should be surfaced when looking for related content. Only set for _index.md of learning path content.
-layout: learningpathall
 ---

content/learning-paths/servers-and-cloud-computing/memcached_cache/_index.md

@@ -51,5 +51,4 @@ further_reading:
 weight: 1                       # _index.md always has weight of 1 to order correctly
 layout: "learningpathall"       # All files under learning paths have this same wrapper
 learning_path_main_page: "yes"  # This should be surfaced when looking for related content. Only set for _index.md of learning path content.
-layout: learningpathall
 ---

content/learning-paths/servers-and-cloud-computing/ml-perf/_index.md

@@ -54,5 +54,4 @@ further_reading:
 weight: 1                       # _index.md always has weight of 1 to order correctly
 layout: "learningpathall"       # All files under learning paths have this same wrapper
 learning_path_main_page: "yes"  # This should be surfaced when looking for related content. Only set for _index.md of learning path content.
-layout: learningpathall
 ---