Remove redundant privilege check from pg_sequences system view.

Remove redundant privilege check from pg_sequences system view.

This commit adjusts pg_sequence_last_value() to return NULL instead
of ERROR-ing for sequences for which the current user lacks
privileges.  This allows us to remove the call to
has_sequence_privilege() in the definition of the pg_sequences
system view.

Bumps catversion.

Suggested-by: Michael Paquier
Reviewed-by: Michael Paquier, Tom Lane
Discussion: https://postgr.es/m/20240501005730.GA594666%40nathanxps13