[TEST-ONLY] Attempt to fix CI failure for ClangModuleVerifier::cachedBuild

Touch some build settings.

Author: cachemeifyoucan

Tests/SWBBuildSystemTests/ClangModuleVerifierTests.swift

@@ -225,6 +225,8 @@ fileprivate struct ClangModuleVerifierTests: CoreBasedTests {
 
                                 "CLANG_ENABLE_COMPILE_CACHE": "YES",
                                 "COMPILATION_CACHE_CAS_PATH": tmpDirPath.join("CompilationCache").str,
+                                "COMPILATION_CACHE_ENABLE_DIAGNOSTIC_REMARKS": "YES",
+                                "COMPILATION_CACHE_LIMIT_SIZE": "20M",
                                 "OTHER_MODULE_VERIFIER_FLAGS": "-- -Rcompile-job-cache",
                                 "DSTROOT": tmpDirPath.join("dstroot").str,
                             ]),