Alternative fix for #22811659 "ACCESSES TO NEW DATA-DICTIONARY ADD CONFUSING STAGES TO P_S.EVENTS_STAGES_*."

Also fixes failure of of group_replication.gr_majority_loss_restart which
popped-up after WL#7743 "New data dictionary: changes to DDL-related parts
of SE API" was implemented.

Do not start "Opening/Locking system tables" stages when we are opening/
locking system tables.

Stages are supposed to be coarse phases of statement execution which are
useful for users to know about (either because they involve lot of work
or some waiting). OTOH, opening/locking system tables are operations which
are normally executed immediately and typically as part of coarser phase
of statement execution. By entering these stages we will either wipe out
or split information about coarser/higher-level stage (there is no concept
of sub-stage yet) without providing much additional value to users.
Therefore this patch removes these two stages which were introduced by
original fix for #22811659.

This also solves problem with group_replication.gr_majority_loss_restart
where access to system tables wiped out information about high-level
"After create" phase, during which commit of CREATE TABLE statement
happens after WL#7743 and which name is used by the test to detect
that CREATE TABLE is blocked during commit.