box: validate global ids after boot in one func

The new function check_global_ids_integrity() checks that the
replicaset UUID specified in the config and found in the data
match. Instance UUID is created at bootstrap and validated at the
beginning of recovery, not in the end. Hence not checked here.

For now this function is not very useful, but soon there will be
more global IDs stored in WAL which will need validation.

Needed for #5029

NO_DOC=refactoring
NO_CHANGELOG=refactoring
NO_TEST=already covered