Speed up Fuzzing workflow (#7856)

This makes a small number of tweaks to `cifuzz.yml` to try to speed up
fuzzing in CI:

* Shorten the fuzz duration to 5 minutes (down from 10)
* Use path filtering to only run on Cirq module code paths
* Target only the `main` branch
* Use build artifact caching
* Use larger GitHub runners

Author: mhucka

.github/workflows/cifuzz.yml

@@ -5,6 +5,10 @@ run-name: >-
 
 on:
   pull_request:
+    branches:
+      - main
+    paths:
+      - 'cirq-*/**'
   workflow_dispatch:
 
 permissions: {}
@@ -17,12 +21,21 @@ concurrency:
 jobs:
   fuzzing:
     name: Fuzz testing
-    runs-on: ubuntu-24.04
+    if: github.repository_owner == 'quantumlib'
+    runs-on: ubuntu-24.04-x64-16-core
     permissions:
       security-events: write
     steps:
     - name: Checkout Code
       uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
+    - name: Cache build artifacts
+      uses: actions/cache@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
+      with:
+        path: |
+          ~/.cache/pip
+          ~/.cache/bazel
+        key: ${{runner.os}}-cifuzz-${{hashFiles('cirq-*/**')}}
+        restore-keys: ${{runner.os}}-cifuzz-
     - name: Build Fuzzers
       id: build
       uses: google/oss-fuzz/infra/cifuzz/actions/build_fuzzers@master
@@ -34,17 +47,17 @@ jobs:
       with:
         oss-fuzz-project-name: cirq
         language: python
-        fuzz-seconds: 600
+        fuzz-seconds: 300
         output-sarif: true
     - name: Upload artifacts to workflow page if a failure occurred
-      uses: actions/upload-artifact@330a01c490aca151604b8cf639adc76d48f6c5d4 # v5.0.0
+      uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
       if: failure() && steps.build.outcome == 'success'
       with:
         name: artifacts
         path: ./out/artifacts
     - name: Upload SARIF file to results page
       if: always() && steps.build.outcome == 'success'
-      uses: github/codeql-action/upload-sarif@d378195403bf7cd9c9b55e4713ede0962aa58b83 # v3
+      uses: github/codeql-action/upload-sarif@25a224b8085c21d4d61b7fc051468805fc3ac490 # codeql-bundle-v2.24.0
       with:
         # This the output SARIF file path generated by the 'run_fuzzers' action.
         sarif_file: cifuzz-sarif/results.sarif