workflows: remove unaccessed files from cache before saving (#452)

Caches are growing organically (started around 400MiB, now at 2+GiB). This strategy is used by github.com/GoogleCloudPlatform/service-extensions to evict unneeded cached entries.

Signed-off-by: Matt Leon <mattleon@google.com>

Author: leonm1

.github/workflows/test.yml

@@ -99,6 +99,15 @@ jobs:
         if-no-files-found: error
         retention-days: 3
 
+    - name: remove unaccessed files from cache
+      shell: bash
+      run: >
+        find /tmp/bazel/cache
+        -type f
+        -name '*'
+        -amin +360
+        -exec rm {} \;
+
     - name: save bazel cache
       uses: actions/cache/save@v3
       if: always()
@@ -352,6 +361,15 @@ jobs:
         --per_file_copt=src/signature_util.cc,test/signature_util_test.cc@-DPROXY_WASM_VERIFY_WITH_ED25519_PUBKEY=\"$(xxd -p -c 256 test/test_data/signature_key1.pub | cut -b9-)\"
         //test:signature_util_test
 
+    - name: remove unaccessed files from cache
+      shell: bash
+      run: >
+        find /tmp/bazel/cache
+        -type f
+        -name '*'
+        -amin +360
+        -exec rm {} \;
+
     - name: save bazel cache
       uses: actions/cache/save@v3
       if: always()