Revert "featureflag: Default-enable Go port of ResolveConflicts RPC"
Gitaly version is failing to be updated due to failing tests related to conflict resolving. This is likely occurring due to the Go port feature flag being switched on in 16ea7b9f. To unblock the deploys, let's revert the feature flag to off by default.
Failing job: https://gitlab.com/gitlab-org/gitlab/-/jobs/1179569930