Fix alpine failures by switching default back to only warn on verification failures. To prevent build failures due to missing GPG or rotated vendor keys. (#1262)

Also allow multiple GPG keys to be provided.

Co-authored-by: John <1615532+johnoliver@users.noreply.github.com>

__tests__/cleanup-java.test.ts

@@ -393,7 +393,7 @@ function createRegisteredJdk(version = '21.0.8+9') {
     architecture: 'x64',
     version,
     source: `sha256:${path.basename(root)}`,
-    verification: 'unverified',
+    verification: 'disabled',
     path: jdkPath
   };
   registerJdk(jdk);