test: canonicalize test-group structure (standalone QA group, group folders)

Make the root test layout match the OrdinaryDiffEq canonical pattern: every
test lives in exactly one group, each group in its own capitalized test/<Group>/
folder, dep-adding groups have their own Project.toml (excluded from the light
main env), and the version matrix is consistent between CI and test_groups.toml.

- Split QA (Aqua) out of the Core branch into a standalone QA group keyed on
  GROUP == "QA" || GROUP == "All", running in its dep-adding test/QA env. Add a
  dedicated QA matrix row to CI.yml restricted to [lts, 1] (excluded on pre),
  so QA no longer runs inside the functional Core job.
- Normalize sublib test_groups.toml [Core] versions ["lts","1.11","1","pre"] ->
  ["lts","1","pre"] for all three sublibraries.
- Move the loose root Core test files into test/Core/, including the previously
  orphaned partitions_and_static_arrays.jl which was never wired into runtests
  and is now part of the Core group. Capitalize the remaining group folders
  (downstream->Downstream, gpu->GPU, nopre->NoPre, qa->QA) and route the
  SymbolicIndexingInterface and NoPre tests into their own group folders so all
  group folder names match their CI GROUP names.

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: ChrisRackauckas

.github/workflows/CI.yml

@@ -28,13 +28,17 @@ jobs:
           - "pre"
         group:
           - "Core"
+          - "QA"
           - "SymbolicIndexingInterface"
           - "Downstream"
           - "NoPre"
         exclude:
           # JET (NoPre) is not run on prereleases.
           - version: "pre"
             group: "NoPre"
+          # QA (Aqua) runs only on lts and 1, never on prereleases.
+          - version: "pre"
+            group: "QA"
     uses: "SciML/.github/.github/workflows/tests.yml@v1"
     with:
       julia-version: "${{ matrix.version }}"
@@ -44,7 +48,7 @@ jobs:
       coverage-directories: "src,ext"
     secrets: "inherit"
 
-  # GPU tests are a dep-adding group (test/gpu/Project.toml) that runs on the
+  # GPU tests are a dep-adding group (test/GPU/Project.toml) that runs on the
   # self-hosted GPU runner. Folded in from the former bespoke GPU.yml.
   gpu:
     name: "GPU Tests"

lib/RecursiveArrayToolsArrayPartitionAnyAll/test/test_groups.toml

@@ -1,2 +1,2 @@
 [Core]
-versions = ["lts", "1.11", "1", "pre"]
+versions = ["lts", "1", "pre"]

lib/RecursiveArrayToolsRaggedArrays/test/test_groups.toml

@@ -1,2 +1,2 @@
 [Core]
-versions = ["lts", "1.11", "1", "pre"]
+versions = ["lts", "1", "pre"]

lib/RecursiveArrayToolsShorthandConstructors/test/test_groups.toml

@@ -1,2 +1,2 @@
 [Core]
-versions = ["lts", "1.11", "1", "pre"]
+versions = ["lts", "1", "pre"]