[gha] fall back to default image

Use base image for CI to work around GHA image pulling issue.
These additional changes are needed to make that work:
- disable mount point
- manual install golang due to old debian mirror
- increase job timeout for the added time in toolchain prep
- upgrade to ubuntu-20.04
- bump serdes-reflection and serdes-generate

Closes: #9536

.github/actions/build-setup/action.yml

@@ -40,6 +40,16 @@ runs:
           mv /Users/runner/work/diem/diem /opt/git/diem
           ln -s /opt/git/diem /Users/runner/work/diem/diem
           cd /opt/git/diem
+        else
+          # FIXME delete after GHA image pull outage; this temporarily sets up
+          # the work dir that the rest of the workflow depends on.
+          if [[ ! -d /opt/git/diem ]]; then
+            sudo mkdir -p /opt/git && sudo mkdir -p /opt/cargo
+            sudo chmod -R g+rw /opt/
+            mv /home/runner/work/diem/diem /opt/git/diem
+            ln -s /opt/git/diem /home/runner/work/diem/diem
+            cd /opt/git/diem
+          fi
         fi
 
         # prepare move lang prover tooling.

.github/actions/build-teardown/action.yml

@@ -5,7 +5,8 @@ runs:
   using: "composite"
   steps:
     - name: Check for changed and untracked files
-      run: ./scripts/changed-files.sh
+      run: |
+        ./scripts/changed-files.sh
       shell: bash
     - name: Clean target directory
       run: |

.github/workflows/ci-post-land.yml

@@ -16,7 +16,7 @@ env:
 
 jobs:
   prepare:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     outputs:
       changes-target-branch: ${{ steps.changes.outputs.changes-target-branch }}
       changes-base-git-rev: ${{ steps.changes.outputs.changes-base-git-rev }}
@@ -59,11 +59,11 @@ jobs:
     if: ${{ needs.prepare.outputs.rust-changes == 'true' }}
     environment:
       name: Sccache
-    runs-on: ubuntu-latest-xl
-    container:
-      image: diem/build_environment:${{ needs.prepare.outputs.changes-target-branch }}
-      volumes:
-        - "${{github.workspace}}:/opt/git/diem"
+    runs-on: ubuntu-20.04-xl
+      #container:
+      #image: diem/build_environment:${{ needs.prepare.outputs.changes-target-branch }}
+      #volumes:
+      #  - "${{github.workspace}}:/opt/git/diem"
     steps:
       - uses: actions/[email protected]
         with:
@@ -90,14 +90,14 @@ jobs:
   # update this report to differentiate branches.
   unit-test-allure-report:
     name: Unit Test Reports
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     if: ${{ github.ref == 'refs/heads/main' }}
     environment:
       name: Sccache
-    container:
-      image: diem/build_environment:main
-      volumes:
-        - "${{github.workspace}}:/opt/git/diem"
+    #container:
+      #image: diem/build_environment:main
+      #volumes:
+      #  - "${{github.workspace}}:/opt/git/diem"
     steps:
       - uses: actions/[email protected]
         with:
@@ -125,7 +125,7 @@ jobs:
 
   build_ci_base_docker_image:
     needs: prepare
-    runs-on: ubuntu-latest-xl
+    runs-on: ubuntu-20.04-xl
     if: ${{ needs.prepare.outputs.base-image-changes == 'true' || github.event_name == 'create' }}
     continue-on-error: false
     env:
@@ -238,7 +238,7 @@ jobs:
 
   build-release-images:
     needs: prepare
-    runs-on: ubuntu-latest-xl
+    runs-on: ubuntu-20.04-xl
     continue-on-error: false
     env:
       TAG: github-1
@@ -330,11 +330,11 @@ jobs:
   rustdoc:
     needs: prepare
     if: ${{ needs.prepare.outputs.changes-target-branch == 'main' && needs.prepare.outputs.rust-changes == 'true'}}
-    runs-on: ubuntu-latest
-    container:
-      image: diem/build_environment:${{ needs.prepare.outputs.changes-target-branch }}
-      volumes:
-        - "${{github.workspace}}:/opt/git/diem"
+    runs-on: ubuntu-20.04
+      #container:
+      #image: diem/build_environment:${{ needs.prepare.outputs.changes-target-branch }}
+      #volumes:
+      #  - "${{github.workspace}}:/opt/git/diem"
     steps:
       - name: Checkout repository
         uses: actions/[email protected]