This script
1. Uses the Phabricator `differential.query` API to determine which revisions of diffs are no longer relevant (because the diffs have been closed or abandoned)
2. Writes a **new shell script** with a series of `git` commands to remove the git tags associated with those no longer relevant revisions.
The way this script will be used on the CI will be something like:
```
cd scripts && node generate-phab-removal-script.js
chmod +x tag_removal_script.sh
./tag_removal_script.sh
```