[VAULT-20630] CI: Use 'ref' (not 'base_ref') as a default git reference to check out code in the test-go GHA workflow (#23458) (#23469)

Co-authored-by: Kuba Wieczorek <kuba.wieczorek@hashicorp.com>

.github/workflows/ci.yml

@@ -60,7 +60,7 @@ jobs:
         with:
           github-token: ${{ secrets.ELEVATED_GITHUB_TOKEN }}
           no-restore: true # don't download them on a cache hit
-      # control checking out head instead of ref by a GH label
+      # control checking out head instead of default ref by a GH label
       # if checkout-head label is added to a PR, checkout HEAD otherwise checkout ref
       - if: ${{ !contains(github.event.pull_request.labels.*.name, 'checkout-head') }}
         run: echo "CHECKOUT_REF=${{ github.ref }}" >> "$GITHUB_ENV"

.github/workflows/test-go.yml

@@ -55,7 +55,7 @@ on:
       checkout-ref:
         description: The ref to use for checkout.
         required: false
-        default: ${{ github.base_ref }}
+        default: ${{ github.ref }}
         type: string
 
 env: ${{ fromJSON(inputs.env-vars) }}