Refactor existing telemetry diagnostics to use makeTelemetryDiagnostic

Refactored bundle-download-telemetry and zstd-availability diagnostics
in init-action.ts to use the new makeTelemetryDiagnostic helper function.
Also added guard for empty languages array in logGitVersionTelemetry.

Co-authored-by: henrymercer <14129055+henrymercer@users.noreply.github.com>

src/git-utils.ts

@@ -88,9 +88,11 @@ export async function logGitVersionTelemetry(
   logger: Logger,
 ): Promise<void> {
   const version = await getGitVersion(logger);
-  if (version !== undefined) {
+  if (version !== undefined && config.languages.length > 0) {
     addDiagnostic(
       config,
+      // Arbitrarily choose the first language. We could also choose all languages, but that
+      // increases the risk of misinterpreting the data.
       config.languages[0],
       makeTelemetryDiagnostic(
         "codeql-action/git-version-telemetry",