test: remove GHSA advisory IDs from test descriptions and comments

Strip advisory identifiers (GHSA-*) from describe blocks, test
docblocks, and inline comments. Replace with plain descriptive
labels. Also clean up FQCNs to use imported class names and minor
style fixes (string concatenation spacing).

tests/Unit/GitRefValidationTest.php

@@ -4,7 +4,7 @@ use App\Models\Application;
 use App\Models\ApplicationSetting;
 
 /**
- * Security tests for git ref validation (GHSA-mw5w-2vvh-mgf4).
+ * Tests for git ref validation.
  *
  * Ensures that git_commit_sha and related inputs are validated
  * to prevent OS command injection via shell metacharacters.