ci: migrate Bazel setup away from archived setup-bazelisk (#19851)

## Why

All Bazel CI jobs are currently blocked in the `setup-bazelisk` step
while trying to download Bazelisk.
[`bazelbuild/setup-bazelisk`](https://github.com/bazelbuild/setup-bazelisk)
is archived, and its README now recommends migrating to
[`bazel-contrib/setup-bazel`](https://github.com/bazel-contrib/setup-bazel),
so leaving our workflows on the archived action leaves CI exposed to
exactly this sort of outage.

Because `v8-canary` now consumes the shared local `setup-bazel-ci`
action, that workflow also needs to trigger when the action changes.
Without that follow-up, Bazel bootstrap regressions specific to the V8
canary path could be skipped by the workflow path filters.

## What Changed

- Switched `.github/actions/setup-bazel-ci/action.yml` from
`bazelbuild/setup-bazelisk` to `bazel-contrib/setup-bazel`, pinned to
`0.19.0`.
- Left `bazelisk-version` unset so GitHub-hosted runners can use their
preinstalled Bazelisk instead of downloading `1.x` at job start.
- Updated `.github/workflows/rusty-v8-release.yml` and
`.github/workflows/v8-canary.yml` to use the shared `setup-bazel-ci`
action instead of referencing `setup-bazelisk` directly.
- Added `.github/actions/setup-bazel-ci/**` to the `pull_request` and
`push` path filters in `.github/workflows/v8-canary.yml` so changes to
the shared Bazel setup action still run the canary workflow.
- Kept the existing repository-cache and Windows-specific Bazel setup
logic intact.

This keeps Bazel version selection anchored by `.bazelversion` while
removing the failing dependency on the archived setup action.

## Verification

- Searched `.github/` to confirm there are no remaining `setup-bazelisk`
references.
- Parsed the updated workflow and action YAML locally with Ruby's
`YAML.load_file`.

.github/workflows/rusty-v8-release.yml

@@ -78,7 +78,9 @@ jobs:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
 
       - name: Set up Bazel
-        uses: bazelbuild/setup-bazelisk@b39c379c82683a5f25d34f0d062761f62693e0b2 # v3
+        uses: ./.github/actions/setup-bazel-ci
+        with:
+          target: ${{ matrix.target }}
 
       - name: Set up Python
         uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6

.github/workflows/v8-canary.yml

@@ -3,6 +3,7 @@ name: v8-canary
 on:
   pull_request:
     paths:
+      - ".github/actions/setup-bazel-ci/**"
       - ".github/scripts/rusty_v8_bazel.py"
       - ".github/workflows/rusty-v8-release.yml"
       - ".github/workflows/v8-canary.yml"
@@ -16,6 +17,7 @@ on:
     branches:
       - main
     paths:
+      - ".github/actions/setup-bazel-ci/**"
       - ".github/scripts/rusty_v8_bazel.py"
       - ".github/workflows/rusty-v8-release.yml"
       - ".github/workflows/v8-canary.yml"
@@ -75,7 +77,9 @@ jobs:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
 
       - name: Set up Bazel
-        uses: bazelbuild/setup-bazelisk@b39c379c82683a5f25d34f0d062761f62693e0b2 # v3
+        uses: ./.github/actions/setup-bazel-ci
+        with:
+          target: ${{ matrix.target }}
 
       - name: Set up Python
         uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6