Move `linux_x64_bazel` job back to running on every commit. (#18560)

Follow-up to https://github.com/iree-org/iree/pull/18533. Build
configuration errors are too easy to make without this running on
presubmit. The long runtime of this job is unfortunate (20-25 minutes
when it could be 2-5 minutes), so we're looking at setting up a new
remote build cache server:
https://github.com/iree-org/iree/issues/18557.

ci-exactly: linux_x64_bazel
diff --git a/.github/workflows/ci_linux_x64_bazel.yml b/.github/workflows/ci_linux_x64_bazel.yml
index 3e5fd71..62af69b 100644
--- a/.github/workflows/ci_linux_x64_bazel.yml
+++ b/.github/workflows/ci_linux_x64_bazel.yml
@@ -7,13 +7,11 @@
 name: CI - Linux x64 bazel
 
 on:
-  pull_request:
-    paths:
-      - ".github/workflows/ci_linux_x64_bazel.yml"
-  schedule:
-    # Weekday mornings at 09:15 UTC = 01:15 PST (UTC - 8).
-    - cron: "15 9 * * 1-5"
   workflow_dispatch:
+  pull_request:
+  push:
+    branches:
+      - main
 
 concurrency:
   # A PR number if a pull request and otherwise the commit hash. This cancels
@@ -24,7 +22,12 @@
   cancel-in-progress: true
 
 jobs:
+  setup:
+    uses: ./.github/workflows/setup.yml
+
   linux_x64_bazel:
+    needs: setup
+    if: contains(fromJson(needs.setup.outputs.enabled-jobs), 'linux_x64_bazel')
     runs-on: azure-linux-scale
     container:
       image: ghcr.io/iree-org/cpubuilder_ubuntu_jammy_x86_64@sha256:2b2ad51d7de988be13086bc618d89d2ba47fbf09eb5b38c60dce82b595fb1c74
diff --git a/docs/website/docs/developers/general/contributing.md b/docs/website/docs/developers/general/contributing.md
index e5b55800..1d638be 100644
--- a/docs/website/docs/developers/general/contributing.md
+++ b/docs/website/docs/developers/general/contributing.md
@@ -389,6 +389,12 @@
     ci-exactly: build_packages,test_onnx
     ```
 
+* Only run Bazel builds, e.g. for changes only affecting Bazel rules:
+
+    ``` text
+    ci-exactly: linux_x64_bazel
+    ```
+
 For example, this PR opted in to running the `build_test_all_windows` job:
 
 ![ci-extra](./contributing-ci-extra.png)
diff --git a/docs/website/docs/developers/general/github-actions.md b/docs/website/docs/developers/general/github-actions.md
index b91007c..5b3c7ae 100644
--- a/docs/website/docs/developers/general/github-actions.md
+++ b/docs/website/docs/developers/general/github-actions.md
@@ -134,7 +134,7 @@
 [`ci_linux_x64_clang_debug.yml`](https://github.com/iree-org/iree/blob/main/.github/workflows/ci_linux_x64_clang_debug.yml) | [![CI - Linux x64 clang debug](https://github.com/iree-org/iree/actions/workflows/ci_linux_x64_clang_debug.yml/badge.svg?query=branch%3Amain+event%3Aschedule)](https://github.com/iree-org/iree/actions/workflows/ci_linux_x64_clang_debug.yml?query=branch%3Amain+event%3Aschedule) | `schedule`
 [`ci_linux_x64_gcc.yml`](https://github.com/iree-org/iree/blob/main/.github/workflows/ci_linux_x64_gcc.yml) | [![CI - Linux x64 gcc](https://github.com/iree-org/iree/actions/workflows/ci_linux_x64_gcc.yml/badge.svg?query=branch%3Amain+event%3Aschedule)](https://github.com/iree-org/iree/actions/workflows/ci_linux_x64_gcc.yml?query=branch%3Amain+event%3Aschedule) | `schedule`
 [`ci_linux_x64_clang_byollvm.yml`](https://github.com/iree-org/iree/blob/main/.github/workflows/ci_linux_x64_clang_byollvm.yml) | [![CI - Linux x64 clang_byollvm](https://github.com/iree-org/iree/actions/workflows/ci_linux_x64_clang_byollvm.yml/badge.svg?query=branch%3Amain+event%3Aschedule)](https://github.com/iree-org/iree/actions/workflows/ci_linux_x64_clang_byollvm.yml?query=branch%3Amain+event%3Aschedule) | `schedule`
-[`ci_linux_x64_bazel.yml`](https://github.com/iree-org/iree/blob/main/.github/workflows/ci_linux_x64_bazel.yml) | [![CI - Linux x64 bazel](https://github.com/iree-org/iree/actions/workflows/ci_linux_x64_bazel.yml/badge.svg?query=branch%3Amain+event%3Aschedule)](https://github.com/iree-org/iree/actions/workflows/ci_linux_x64_bazel.yml?query=branch%3Amain+event%3Aschedule) | `schedule`
+[`ci_linux_x64_bazel.yml`](https://github.com/iree-org/iree/blob/main/.github/workflows/ci_linux_x64_bazel.yml) | [![CI - Linux x64 bazel](https://github.com/iree-org/iree/actions/workflows/ci_linux_x64_bazel.yml/badge.svg?query=branch%3Amain+event%3Apush)](https://github.com/iree-org/iree/actions/workflows/ci_linux_x64_bazel.yml?query=branch%3Amain+event%3Apush) | `pull_request`, `push`
 
 <!-- TODO(scotttodd): the remains of ci.yml (runtime builds, etc.) -->
 <!-- TODO(scotttodd): cross-compilation jobs -->