pgsql: doc: Update REPACK-related table rewrite documentation

doc: Update REPACK-related table rewrite documentation

Adding REPACK introduced table-rewrite behavior that overlaps with
VACUUM FULL and CLUSTER, but some documentation still mentioned only one
of these commands or described the progress and locking behavior
imprecisely.

Clarify that table-rewriting operations, including REPACK, can change
CTIDs. Also describe VACUUM FULL, CLUSTER, and REPACK consistently as
table-rewriting operations for disk-space recovery where appropriate,
document the pg_stat_progress_repack and compatibility
pg_stat_progress_cluster views consistently, and clarify the ACCESS
EXCLUSIVE locking behavior of REPACK, including CONCURRENTLY.

Backpatch to v19, where REPACK was introduced.

Author: Marcos Pegoraro <marcos(at)f10(dot)com(dot)br>
Author: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
Discussion: https://postgr.es/m/CAB-JLwaLcHyf=OnLnBsJEbdd57WjWPpK5T7iGFJvAQphjTZj_A@mail.gmail.com
Backpatch-through: 19

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/872b20aa5649f9b90781961cbc404409783dab2b

Modified Files
--------------
doc/src/sgml/ddl.sgml | 4 +++-
doc/src/sgml/maintenance.sgml | 45 ++++++++++++++++++++++++++-----------------
doc/src/sgml/monitoring.sgml | 24 +++++++++++++----------
doc/src/sgml/mvcc.sgml | 12 ++++++++----
4 files changed, 52 insertions(+), 33 deletions(-)