More network flake improvements (#31)

* Gracefully fallback to local builds on server failures

* Force update submodules on failure

Author: mkruskal-google

checkout/action.yml

@@ -39,4 +39,4 @@ runs:
         max_attempts: 5
         shell: bash
         command: |
-          git submodule update --init ${{ inputs.submodules == 'recursive' && '--recursive' || '' }}
+          git submodule update --force --init ${{ inputs.submodules == 'recursive' && '--recursive' || '' }}

sccache/action.yml

@@ -59,6 +59,7 @@ runs:
         echo "SCCACHE_GCS_BUCKET=protobuf-sccache" >> $GITHUB_ENV
         echo "SCCACHE_GCS_KEY_PREFIX=${{ inputs.cache-prefix }}" >> $GITHUB_ENV
         echo "SCCACHE_IDLE_TIMEOUT=0" >> $GITHUB_ENV
+        echo "SCCACHE_IGNORE_SERVER_IO_ERROR=1" >> $GITHUB_ENV
 
     # Only trusted runs should have write access to our caches.
     - name: Enable sccache cache writing
@@ -81,6 +82,7 @@ runs:
         retry_wait_seconds: 60
         max_attempts: 5
         shell: bash
+        continue_on_error: true
         command: sccache --start-server
 
     - name: Configure sccache cmake arguments