Do not fail github-actions even when archiving artifacts fails

Uploading github-actions artifacts is extremely flaky. Just look at
actions/upload-artifact#84 (comment)
(Note the many +1 on the issue even after the issue has been closed.).

This tries to make sure that the test isn't marked as failure because
archiving the artifacts failed on some files.

pr-link: #12328
change-id: cid-72f6694761bfc3a88a62ca0422deee116779e6be

.github/workflows/checkstyle.yml

@@ -36,6 +36,7 @@ jobs:
         timeout-minutes: 60
 
       - name: Archive artifacts
+        continue-on-error: true
         uses: actions/upload-artifact@v2
         if: always()
         with:

.github/workflows/java11_integration_tests.yml

@@ -58,6 +58,7 @@ jobs:
         timeout-minutes: 60
 
       - name: Archive artifacts
+        continue-on-error: true
         uses: actions/upload-artifact@v2
         if: always()
         with:

.github/workflows/java11_unit_tests.yml

@@ -46,6 +46,7 @@ jobs:
         timeout-minutes: 60
 
       - name: Archive artifacts
+        continue-on-error: true
         uses: actions/upload-artifact@v2
         if: always()
         with:

.github/workflows/java8_integration_tests.yml

@@ -57,6 +57,7 @@ jobs:
         timeout-minutes: 60
 
       - name: Archive artifacts
+        continue-on-error: true
         uses: actions/upload-artifact@v2
         if: always()
         with:

.github/workflows/java8_unit_tests.yml

@@ -45,6 +45,7 @@ jobs:
         timeout-minutes: 60
 
       - name: Archive artifacts
+        continue-on-error: true
         uses: actions/upload-artifact@v2
         if: always()
         with: