revert(ci): remove temporary v0.1.6 protobuf exception (#4978)

Reverts ac7f615cd1 after successful v0.1.6 publication.

Signed-off-by: Taylor Mutch <taylormutch@gmail.com>

.github/workflows/release-qualification.yml

@@ -30,10 +30,6 @@ permissions:
 
 env:
   RELEASE_TAG: ${{ inputs.release-tag }}
-  # TEMPORARY (#4976): squash-merge and revert after v0.1.6 publication is verified.
-  # See CI.md's "Remove the v0.1.6 exception" procedure.
-  PROTO_COMPATIBILITY_EXCEPTION_TAG: ${{ inputs.is-prerelease && startsWith(inputs.release-tag, 'v0.1.6-pre.') && inputs.release-tag || '' }}
-  PROTO_COMPATIBILITY_EXCEPTION_REASON: Release captain accepted protobuf breaking changes for the v0.1.6 prerelease train; migration guidance must accompany the release.
 
 defaults:
   run:
@@ -216,11 +212,6 @@ jobs:
             echo "| Docker E2E | ${DOCKER_E2E_RESULT} |"
             echo "| VM E2E | ${VM_E2E_RESULT} |"
             echo
-            if [[ -n "${PROTO_COMPATIBILITY_EXCEPTION_TAG}" ]]; then
-              echo "- Protobuf compatibility exception: \`${PROTO_COMPATIBILITY_EXCEPTION_TAG}\`"
-              echo "- Reason: ${PROTO_COMPATIBILITY_EXCEPTION_REASON}"
-              echo
-            fi
             echo "Advisory compatibility findings do not affect the qualification result."
             echo "See the Compatibility Review job and compatibility-review-run-${GITHUB_RUN_ID}-attempt-${GITHUB_RUN_ATTEMPT} artifact in [this run](${run_url})."
           } >> "${GITHUB_STEP_SUMMARY}"