fix(cli) do not print out stacktraces when running `kong migrations up` with pending migrations
fix(cli) do not print out stacktraces when running `kong migrations up` with pending migrations

Fixes #6105 reported by @jeremyjpj0916. The stacktrace is not necessary as it is not a real error, but just a way for us to get out of the cluster mutex callback.

In the future we may want to allow cluster mutex to handle error messages more gracefully, but for now this change is sufficient without significant modification to the cluster mutex helper.

Before this commit:
```
$ kong migrations up
Error: [PostgreSQL error] cluster_mutex callback threw an error: kong/cmd/utils/migrations.lua:67: Database has pending migrations; run 'kong migrations finish'
stack traceback:
	[C]: in function 'error'
	kong/cmd/utils/migrations.lua:67: in function <kong/cmd/utils/migrations.lua:63>
	[C]: in function 'xpcall'
	kong/db/init.lua:364: in function <kong/db/init.lua:314>
	[C]: in function 'pcall'
	kong/concurrency.lua:45: in function 'cluster_mutex'
	kong/cmd/utils/migrations.lua:63: in function 'up'
	kong/cmd/migrations.lua:177: in function 'cmd_exec'
	kong/cmd/init.lua:88: in function <kong/cmd/init.lua:88>
	[C]: in function 'xpcall'
	kong/cmd/init.lua:88: in function <kong/cmd/init.lua:45>
	bin/kong:9: in function 'file_gen'
	init_worker_by_lua:47: in function <init_worker_by_lua:45>
	[C]: in function 'xpcall'
	init_worker_by_lua:54: in function <init_worker_by_lua:52>

  Run with --v (verbose) or --vv (debug) for more details
```

After this commit:
```
$ kong migrations up
Error: Database has pending migrations; run 'kong migrations finish'

  Run with --v (verbose) or --vv (debug) for more details
```

Co-authored-by: Datong Sun <88ea7fe5b18d86dd626610096bab9e86520f1a58@konghq.com>
Kong/kong,Kong/kong,Kong/kong