Optimize CIFuzz workflow cache

- Remove unused bazel cache path.
- Update cache key to hash dependency files (setup.py, pyproject.toml, requirements.txt) instead of all source files. This improves cache hit rate for PRs that do not modify dependencies.
- Format the cache key definition for better readability.

Co-authored-by: mhucka <1450019+mhucka@users.noreply.github.com>

Author: google-labs-jules[bot]

.github/workflows/cifuzz.yml

@@ -33,7 +33,15 @@ jobs:
       with:
         path: |
           ~/.cache/pip
-        key: ${{runner.os}}-cifuzz-${{hashFiles('setup.py', 'pyproject.toml', 'dev_tools/requirements/**/*.txt', 'cirq-*/setup.py', 'cirq-*/pyproject.toml', 'cirq-*/**/requirements.txt')}}
+        key: >-
+          ${{runner.os}}-cifuzz-${{hashFiles(
+          'setup.py',
+          'pyproject.toml',
+          'dev_tools/requirements/**/*.txt',
+          'cirq-*/setup.py',
+          'cirq-*/pyproject.toml',
+          'cirq-*/**/requirements.txt'
+          )}}
         restore-keys: ${{runner.os}}-cifuzz-
     - name: Build Fuzzers
       id: build