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>

.github/workflows/run_license_checks.yml

@@ -0,0 +1,51 @@
+# Generated from xtask::workflows::run_license_checks
+# Rebuild with `cargo xtask workflows`.
+name: run_license_checks
+env:
+  CARGO_TERM_COLOR: always
+  RUST_BACKTRACE: '1'
+  CARGO_INCREMENTAL: '0'
+on:
+  pull_request:
+    branches:
+    - '**'
+    paths:
+    - Cargo.lock
+    - '**/Cargo.lock'
+    - script/*licenses
+    - '**/LICENSE*'
+    - .github/workflows/run_license_checks.yml
+  push:
+    branches:
+    - main
+    - v[0-9]+.[0-9]+.x
+    paths:
+    - Cargo.lock
+    - '**/Cargo.lock'
+    - script/*licenses
+    - '**/LICENSE*'
+    - .github/workflows/run_license_checks.yml
+jobs:
+  check_licenses:
+    runs-on: namespace-profile-2x4-ubuntu-2404
+    steps:
+    - name: steps::checkout_repo
+      uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+      with:
+        clean: false
+    - name: ./script/check-licenses
+      run: ./script/check-licenses
+      shell: bash -euxo pipefail {0}
+  build_licenses:
+    runs-on: namespace-profile-4x8-ubuntu-2204
+    steps:
+    - name: steps::checkout_repo
+      uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+      with:
+        clean: false
+    - name: ./script/generate-licenses
+      run: ./script/generate-licenses
+      shell: bash -euxo pipefail {0}
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref_name }}-${{ github.ref_name == 'main' && github.sha || 'anysha' }}
+  cancel-in-progress: true