ci: reduce number of simtest seeds for most PRs (#3120)

Author: mlegner

.github/workflows/code.yml

@@ -144,6 +144,10 @@ jobs:
     env:
       # Turn off Sui logging since it can be very distractive in CI
       RUST_LOG: simtest=info,error,sui_=off,consensus_core=off
+      # Default: 2 seeds (1 without gRPC, 1 with gRPC). Pushes to main and PRs
+      # with the `ci:more-simtest-seeds` label run all 5 seeds.
+      SIMTEST_FULL: ${{ github.event_name == 'push' || contains(github.event.pull_request.labels.*.name, 'ci:more-simtest-seeds')
+        }}
     steps:
       - uses: taiki-e/install-action@970d55e3ce02a46d60ffae7b4fab3dedace6e769 # pin@v2.49.13
         with:
@@ -156,13 +160,16 @@ jobs:
       - run: ./scripts/simtest/install.sh
       - name: Run tests (seed=1)
         run: MSIM_TEST_SEED=1 cargo simtest simtest --profile simtest
-      - name: Run tests (seed=2)
-        run: MSIM_TEST_SEED=2 cargo simtest simtest --profile simtest
-      - name: Run tests (seed=3, grpc-client-enabled)
-        run: MSIM_TEST_SEED=3 WALRUS_GRPC_MIGRATION_LEVEL=100 cargo simtest simtest --profile simtest
+      - name: Run tests (seed=2, grpc-client-enabled)
+        run: MSIM_TEST_SEED=2 WALRUS_GRPC_MIGRATION_LEVEL=100 cargo simtest simtest --profile simtest
+      - name: Run tests (seed=3)
+        if: env.SIMTEST_FULL == 'true'
+        run: MSIM_TEST_SEED=3 cargo simtest simtest --profile simtest
       - name: Run tests (seed=4, grpc-client-enabled)
+        if: env.SIMTEST_FULL == 'true'
         run: MSIM_TEST_SEED=4 WALRUS_GRPC_MIGRATION_LEVEL=100 cargo simtest simtest --profile simtest
       - name: Run tests (seed=5, grpc-client-enabled)
+        if: env.SIMTEST_FULL == 'true'
         run: MSIM_TEST_SEED=5 WALRUS_GRPC_MIGRATION_LEVEL=100 cargo simtest simtest --profile simtest
 
   simtests-build: