## Summary
- rename the `allow_in_plan_mode` migration pair from `000472` to
`000473`
- rename the matching fixture file and update its comment
- remove the duplicate migration version that broke containerized
database startup
## Testing
- `go test ./coderd/database/migrations -run '^TestMigrate$' -count=1
-timeout 15m`
- validated `iofs.New` for `coderd/database/migrations` and
`coderd/database/migrations/testdata/fixtures`
Closescoder/internal#1483
> Mux opened this PR on Mike's behalf.