Do not hardcode default Priority names in Project Reports tooltip
Summary:
Pull the names of Priority field values instead of hardcoding them.
Closes T15799
Test Plan:
* As an admin, go to `/config/edit/maniphest.priorities/` and change the value of `"name"` of a Priority value with a value < `50` (e.g.: Low, Wishlist)
* Open `/maniphest/report/project/`
* Hover over the `Oldest (Pri)` column and check the tooltip text before and after applying this patch
Reviewers: O1 Blessed Committers, valerio.bozzolan
Reviewed By: O1 Blessed Committers, valerio.bozzolan
Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno
Maniphest Tasks: T15799
Differential Revision: https://we.phorge.it/D25602