Use gh workflow for tests (#41384)

Follow up for: #41304

Splits CI tests (cherry-picks and PRs only for now) into separate
workflows using `gh-workflow`. Includes a couple restructures to
- run more things in parallel
- remove our previous shell script based checking to filter tests based
on files changed, instead using the builtin `paths:` workflow filters


Splitting the docs/style/rust tests & checks into separate workflows
means we lose the complete summary showing all the tests in one view,
but it's possible to re-add in the future if we go back to checking what
files changed ourselves or always run everything.

Release Notes:

- N/A *or* Added/Fixed/Improved ...

---------

Co-authored-by: Conrad <conrad@zed.dev>

docs/src/vim.md

@@ -628,7 +628,7 @@ Here's an example of these settings changed:
   // Allow the cursor to reach the edges of the screen
   "vertical_scroll_margin": 0,
   "gutter": {
-    // Disable line numbers completely:
+    // Disable line numbers completely
     "line_numbers": false
   },
   "command_aliases": {