Revert "Merge branch 'session-prefix-fallback-firstcell' into 'main'"
This reverts merge request !282 (merged)
As we want to rollout session_prefix
in gitlab-org&14577, we need to revert this. Why ? Because FIRST_CELL relies on topology service having the first cell, and we do not intend to connect legacy cell to Topology service until Phase 6.