[ci] disable workspace-hack before testing on powerpc

The workspace-hack tries to enable ring and openssl on powerpc. The
former can't be built on powerpc at all, and the latter is somewhat
tricky to do so. Since we only care about a subset of crates on
powerpc anyway, it is ok to just disable the workspace-hack there.

.github/workflows/ci-test.yml

@@ -809,7 +809,12 @@ jobs:
       - run: $pre_command && cargo xcheck -j ${max_threads} --workspace --all-targets
       - run: |
           $pre_command && rustup target add powerpc-unknown-linux-gnu
+          # disable the workspace-hack because it contains some code that doesn't build on powerpc
+          $pre_command && cargo x generate-workspace-hack --mode disable
           $pre_command && cargo xcheck -j ${max_threads} -p diem-transaction-builder -p move-vm-types --target powerpc-unknown-linux-gnu
+          # we can't just re-enable the workspace-hack at the end, because it can result in a different
+          # Cargo.lock resolution result in some cases. So use git reset instead.
+          $pre_command && git reset --hard HEAD
       - uses: ./.github/actions/build-teardown
       - name: Early terminate workflow
         if: ${{ failure() }}