fix: use BUN_LOCK instead of non-existent BUN_LEGACY

Author: abidhasan-aws

packages/aws-cdk-lib/aws-cloudfront/lib/experimental/nodejs-edge-function.ts

@@ -108,7 +108,7 @@ function findLockFile(scope: Construct, depsLockFilePath?: string): string {
     LockFile.YARN,
     LockFile.NPM,
     LockFile.BUN,
-    LockFile.BUN_LEGACY,
+    LockFile.BUN_LOCK,
   ]);
 
   if (lockFiles.length === 0) {