test: merge ongc and gcutil into gc.js

Description

This pull request merges the ongc.js file and the gcUntil function from common/index.js into a single file. This addresses the TODO comment.

https://github.com/nodejs/node/pull/54355/files#diff-7bb0a76e3c72f10092fee1af7885f0dd5555b6b01eca36e82514104a79b7c9ceL5

Changes Made

1. Merged the contents of ongc.js and the gcUntil function from common/index.js into the gc.js file.
2. Updated any necessary imports or exports.
3. Removed the original ongc.js file.

Tests

• Added/updated tests for the merged functionality
• Ensured all existing tests pass

Documentation

• Updated relevant documentation, if necessary