fix(ci): Fix YAML syntax error in glibc-validation script

Remove escaped backslashes from grep regex pattern that were causing
GitLab CI/CD parser to fail with 'script config should be a string'
error.

Changed: libstdc\+\+ → libstdc (still matches libstdc++.so.6)

.gitlab-ci.yml

@@ -173,7 +173,7 @@ test:glibc-validation:
 
     # Test 3: Verify base system libraries
     - echo "Test 3: Verifying base system libraries..."
-    - docker run --rm $IMAGE_TAG ldconfig -p | grep -E "(libstdc\+\+|libgcc_s|libm\.so|libc\.so)"
+    - docker run --rm $IMAGE_TAG ldconfig -p | grep -E "(libstdc|libgcc_s|libm\.so|libc\.so)"
 
     # Test 4: Verify ca-certificates
     - echo "Test 4: Verifying ca-certificates..."