ci: migrate MLA tests to test/registered/mla/ (#15798)

.github/workflows/pr-test.yml

@@ -433,7 +433,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        partition: [0, 1, 2]
+        partition: [0, 1, 2, 3]
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
@@ -454,7 +454,7 @@ jobs:
         timeout-minutes: 30
         run: |
           cd test/
-          python3 run_suite.py --hw cuda --suite stage-b-test-small-1-gpu --auto-partition-id ${{ matrix.partition }} --auto-partition-size 3
+          python3 run_suite.py --hw cuda --suite stage-b-test-small-1-gpu --auto-partition-id ${{ matrix.partition }} --auto-partition-size 4
 
   stage-b-test-large-1-gpu:
     needs: [check-changes, call-gate, stage-a-test-1, sgl-kernel-build-wheels]