VAULT-33693: actions: fix push event PR labels

Fix pull request label metadata when triggered `push` event types.
We now use Github's `associatedPullRequests()` connection on the
`Commit` associated with the SHA to resolve the labels.

Signed-off-by: Ryan Cragun <[email protected]>

.github/actions/metadata/action.yml

@@ -108,15 +108,32 @@ runs:
 
           labels=$(gh api "/repos/${{ github.repository }}/issues/${{ github.event.number }}/labels" | jq -erc '. | map(.name)')
         else
+          # We can assume we're being triggered for a 'push' (a merge)
           is_draft='false'
 
-          # Look up the labels for the pull request that is associated with the last commit. If
-          # there are none set it as a JSON encoded empty array.
-          if pr_number=$(gh api "/repos/${{ github.repository }}/commits/${{ github.ref }}/pulls" | jq -erc '.[0].number'); then
-            if ! labels=$(gh api "/repos/${{ github.repository }}/issues/${pr_number}/labels" | jq -erc '. | map(.name)'); then
-              labels='[]'
-            fi
-          else
+          # Look up the pull request labels for the PR that is associated with
+          # the commit. If there are none set it as a JSON encoded empty array.
+          repo=$(printf ${{ github.repository }} | cut -d "/" -f2)
+          if ! labels=$(gh api graphql -F repo="$repo" -f query='
+            query prLabels($repo: String!){
+              repository(name: $repo, owner: "hashicorp") {
+                commit: object(expression: "${{ steps.vault-metadata.outputs.vault-revision }}") {
+                  ... on Commit {
+                  associatedPullRequests(first:1){
+                    edges{
+                      node{
+                        labels(first: 10) {
+                          nodes {
+                            name
+                          }
+                        }
+                      }
+                    }
+                  }
+                }
+              }
+            }' | jq -erc '.data.repository.commit.associatedPullRequests.edges[0].node.labels.nodes | map(.name)');
+          then
             labels='[]'
           fi
         fi