Revert "Upgrade to clang-r530567"

This reverts commit b4f05f1a05046e184417e12a0081442fac4ec41e.

Reason for revert: <Potential culprit for b/352458178  - verifying through ABTD before revert submission. This is part of the standard investigation process, and does not mean your CL will be reverted.>

Change-Id: Idf6c69296c6537e8011c2ce5fcbdf45a29154acf
diff --git a/cc/config/global.go b/cc/config/global.go
index bf2502f..62a4765 100644
--- a/cc/config/global.go
+++ b/cc/config/global.go
@@ -397,8 +397,8 @@
 
 	// prebuilts/clang default settings.
 	ClangDefaultBase         = "prebuilts/clang/host"
-	ClangDefaultVersion      = "clang-r530567"
-	ClangDefaultShortVersion = "19"
+	ClangDefaultVersion      = "clang-r522817"
+	ClangDefaultShortVersion = "18"
 
 	// Directories with warnings from Android.bp files.
 	WarningAllowedProjects = []string{