chore: revert force deploying main (#23290) (#24072)

⚠️ DO NOT MERGE UNTIL @f0ssel SAYS SO ⚠️ 

This reverts commit 8f78c5145f
(https://github.com/coder/coder/pull/23290).

scripts/should_deploy.sh

@@ -58,10 +58,6 @@ else
 fi
 log "Deploy branch: $deploy_branch"
 
-# TODO: remove this temporary override
-log "OVERRIDE: forcing main as deploy branch"
-deploy_branch=main
-
 # Finally, check if the current branch is the deploy branch.
 log
 if [[ "$branch_name" != "$deploy_branch" ]]; then