PYTHON-5879 Only run sharded_cluster non-standard tasks on PRs

Previously all three topologies (standalone, replica_set, sharded_cluster)
for version=latest were marked pr=True and activated in patch builds.
Limiting to sharded_cluster cuts the patch build task count for non-standard
variants from 3 topology tasks down to 1 (plus its non-coverage companion
for macOS/Win64 encryption variants).

Standalone and replica_set tasks for latest still exist for waterfall builds
but no longer carry the pr tag.

Author: aclark4life

.evergreen/generated_configs/tasks.yml

@@ -4802,32 +4802,6 @@ tasks:
       - python-3.13
       - standalone-noauth-nossl
       - noauth
-  - name: test-non-standard-latest-python3.14t-noauth-ssl-replica-set-cov
-    commands:
-      - func: run server
-        vars:
-          AUTH: noauth
-          SSL: ssl
-          TOPOLOGY: replica_set
-          VERSION: latest
-          COVERAGE: "1"
-      - func: run tests
-        vars:
-          AUTH: noauth
-          SSL: ssl
-          TOPOLOGY: replica_set
-          VERSION: latest
-          COVERAGE: "1"
-          TOOLCHAIN_VERSION: 3.14t
-    tags:
-      - test-non-standard
-      - server-latest
-      - python-3.14t
-      - replica_set-noauth-ssl
-      - noauth
-      - free-threaded
-      - pr
-      - cov
   - name: test-non-standard-latest-python3.14t-noauth-ssl-replica-set
     commands:
       - func: run server
@@ -4844,13 +4818,12 @@ tasks:
           VERSION: latest
           TOOLCHAIN_VERSION: 3.14t
     tags:
-      - test-non-standard-no-cov
+      - test-non-standard
       - server-latest
       - python-3.14t
       - replica_set-noauth-ssl
       - noauth
       - free-threaded
-      - pr
   - name: test-non-standard-latest-pypy3.11-noauth-ssl-replica-set
     commands:
       - func: run server
@@ -4920,31 +4893,6 @@ tasks:
       - sharded_cluster-auth-ssl
       - auth
       - pr
-  - name: test-non-standard-latest-python3.13-noauth-nossl-standalone-cov
-    commands:
-      - func: run server
-        vars:
-          AUTH: noauth
-          SSL: nossl
-          TOPOLOGY: standalone
-          VERSION: latest
-          COVERAGE: "1"
-      - func: run tests
-        vars:
-          AUTH: noauth
-          SSL: nossl
-          TOPOLOGY: standalone
-          VERSION: latest
-          COVERAGE: "1"
-          TOOLCHAIN_VERSION: "3.13"
-    tags:
-      - test-non-standard
-      - server-latest
-      - python-3.13
-      - standalone-noauth-nossl
-      - noauth
-      - pr
-      - cov
   - name: test-non-standard-latest-python3.13-noauth-nossl-standalone
     commands:
       - func: run server
@@ -4961,12 +4909,11 @@ tasks:
           VERSION: latest
           TOOLCHAIN_VERSION: "3.13"
     tags:
-      - test-non-standard-no-cov
+      - test-non-standard
       - server-latest
       - python-3.13
       - standalone-noauth-nossl
       - noauth
-      - pr
   - name: test-non-standard-rapid-python3.11-noauth-ssl-replica-set
     commands:
       - func: run server

.evergreen/scripts/generate_config.py

@@ -648,8 +648,9 @@ def create_test_non_standard_tasks():
     tasks = []
     task_combos = set()
     # For each version and topology, rotate through the CPythons.
+    # Only the sharded_cluster topology runs on PRs to keep patch build size manageable.
     for (version, topology), python in zip_cycle(list(product(ALL_VERSIONS, TOPOLOGIES)), CPYTHONS):
-        pr = version == "latest"
+        pr = version == "latest" and topology == "sharded_cluster"
         task_combos.add((version, topology, python, pr))
     # For each PyPy and topology, rotate through the MongoDB versions.
     for (python, topology), version in zip_cycle(list(product(PYPYS, TOPOLOGIES)), ALL_VERSIONS):