Configure standard .NET OpenSSL trust for Linux tests

The original GitHub job logs show dotnet dev-certs exiting with code 4 before cluster tests because SSL_CERT_DIR does not include the SDK development-certificate trust directory. Set the documented .NET trust path for the SDK command and subsequent clients. No custom CA, PFX generation or TLS validation bypass is introduced.

Validated with actionlint. Runtime source and the frozen local test binaries are unchanged; the complete Linux workflow will verify this environment correction.

Author: KSemenenko

.github/workflows/build-and-tests.yml

@@ -159,7 +159,10 @@ jobs:
             certutil -N -d "sql:$HOME/.pki/nssdb" --empty-password
           fi
       - name: Trust standard Aspire development certificate
-        run: dotnet dev-certs https --trust
+        run: |
+          export SSL_CERT_DIR="$HOME/.aspnet/dev-certs/trust:/usr/lib/ssl/certs"
+          echo "SSL_CERT_DIR=$SSL_CERT_DIR" >> "$GITHUB_ENV"
+          dotnet dev-certs https --trust
       - name: Test Aspire topology lanes
         run: node scripts/Features/TestInfrastructure/ci-test-shards.mjs run "$SHARD" --results-directory "$GITHUB_WORKSPACE/tests/KeyLoad.ClusterTests/bin/Debug/net10.0/ci-results"
       - name: Save test results