pgsql: Add isolation test for TOAST value reuse during CLUSTER

Add isolation test for TOAST value reuse during CLUSTER This test exercises the corner case in toast_save_datum() where CLUSTER operations encounter duplicated TOAST references, reusing the existing TOAST data instead of creating redundant copies. During table rewrites like CLUSTER, both live and

pgsql: Fix typos in comments.

Fix typos in comments. Oversight in commit fd5a1a0c3e56. Author: Tender Wang Discussion: https://postgr.es/m/CAHewXNmTT3M_w4NngG=6g3mdt3ij6ddnctqv9yngxbphw8x...@mail.gmail.com Branch -- master Details --- https://git.postgresql.org/pg/commitdiff/928da6ff1254f471941e43f9ad258cc6b1f037e