Feature summary (what you would like to be able to do and where):
Remove hard-coding of template names from the extension. Move to an on-wiki json file. See {T259835#7518714}
Deletion tags: https://gerrit.wikimedia.org/r/plugins/gitiles/mediawiki/extensions/PageTriage/+/refs/heads/master/modules/ext.pageTriage.tagData/deletionTags.json
Maintenance tags: https://gerrit.wikimedia.org/r/plugins/gitiles/mediawiki/extensions/PageTriage/+/refs/heads/master/modules/ext.pageTriage.tagData/maintenanceTags.json
Use case(s) (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):
Benefits (why should this be implemented?): Changes to any template names will not need any change to the extension code and will be more immediate.