test: removed unused variable in fs-watch-file-slow

PR-URL: #23548
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

test/pummel/test-fs-watch-file-slow.js

@@ -34,7 +34,7 @@ let nevents = 0;
 
 try {
   fs.unlinkSync(FILENAME);
-} catch (e) {
+} catch {
   // swallow
 }