Fix observability tests to use Aspire testing framework and remove stress tests

Co-authored-by: devstress <[email protected]>

Author: Copilot

.github/workflows/build.yml

@@ -76,10 +76,6 @@ jobs:
     needs: build
     uses: ./.github/workflows/reliability-tests.yml
 
-  stress_tests_confluent:
-    needs: build
-    uses: ./.github/workflows/stress-tests-confluent.yml
-
   backpressure_tests:
     needs: build
     uses: ./.github/workflows/backpressure-tests.yml

.github/workflows/observability-tests.yml

@@ -554,7 +554,7 @@ The integration tests are fully integrated with GitHub Actions:
 ```yaml
 # Workflows that use this infrastructure:
 - integration-tests.yml      # Basic infrastructure validation
-- stress-tests-confluent.yml # High-throughput scenarios  
+- observability-tests.yml # Message per second metrics with Aspire testing framework  
 - reliability-tests.yml      # Back pressure and rebalance
 - backpressure-tests.yml     # Flow control validation
 ```