Use Gitaly long timeout for resolving conflicts

Currently the ResolveConflicts RPC can take over 30 seconds to run. When
push rules are enabled, the `/api/v4/internal/allowed` currently takes
about 30 seconds for the gitlab-org/gitlab repository. In addition, with
Gitaly Cluster, since refs updates happen in a transaction, all nodes
also have to acknowledge the ref update for this RPC to finish
successfully. This can add even more time.

Until we solve https://gitlab.com/gitlab-org/gitlab/-/issues/335134,
let's bump the timeout from 30 to 60 seconds to allow for this RPC to do
all its work.

Changelog: changed

lib/gitlab/gitaly_client/conflicts_service.rb

@@ -49,7 +49,7 @@ module Gitlab
           end
         end
 
-        response = GitalyClient.call(@repository.storage, :conflicts_service, :resolve_conflicts, req_enum, remote_storage: target_repository.storage, timeout: GitalyClient.medium_timeout)
+        response = GitalyClient.call(@repository.storage, :conflicts_service, :resolve_conflicts, req_enum, remote_storage: target_repository.storage, timeout: GitalyClient.long_timeout)
 
         if response.resolution_error.present?
           raise Gitlab::Git::Conflict::Resolver::ResolutionError, response.resolution_error