Run ConcurrentSafe tests multiple times in CI (#5759)

This test has a high possibility of detecting issues like #5757.
https://github.com/open-telemetry/opentelemetry-go/actions/runs/10635489400/job/29485188862?pr=5759

We need to merge fixes of #5757, like #5758, first.

.github/workflows/ci.yml

@@ -81,6 +81,20 @@ jobs:
       - name: Run tests with race detector
         run: make test-race
 
+  test-concurrent-safe:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Repo
+        uses: actions/checkout@v4
+      - name: Install Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: ${{ env.DEFAULT_GO_VERSION }}
+          check-latest: true
+          cache-dependency-path: "**/go.sum"
+      - name: Run ConcurrentSafe tests multiple times with race detector
+        run: make test-concurrent-safe
+
   test-coverage:
     runs-on: ubuntu-latest
     steps:

Makefile

@@ -145,12 +145,14 @@ build-tests/%:
 
 # Tests
 
-TEST_TARGETS := test-default test-bench test-short test-verbose test-race
+TEST_TARGETS := test-default test-bench test-short test-verbose test-race test-concurrent-safe
 .PHONY: $(TEST_TARGETS) test
 test-default test-race: ARGS=-race
 test-bench:   ARGS=-run=xxxxxMatchNothingxxxxx -test.benchtime=1ms -bench=.
 test-short:   ARGS=-short
 test-verbose: ARGS=-v -race
+test-concurrent-safe: ARGS=-run=ConcurrentSafe -count=100 -race
+test-concurrent-safe: TIMEOUT=120
 $(TEST_TARGETS): test
 test: $(OTEL_GO_MOD_DIRS:%=test/%)
 test/%: DIR=$*