pgsql: Fix use-after-free issue in slot synchronization.

Fix use-after-free issue in slot synchronization. Author: Shlok Kyal Reviewed-by: Daniel Gustafsson Reviewed-by: Amit Kapila Backpatch-through: 18, where it was introduced Discussion: https://postgr.es/m/canhcyexmrcedzj-rngjam0njhm4y+ttdwsgucfmxcim7bnk...@mail.gmail.com Branch -- REL_18_S

pgsql: Fix use-after-free issue in slot synchronization.

Fix use-after-free issue in slot synchronization. Author: Shlok Kyal Reviewed-by: Daniel Gustafsson Reviewed-by: Amit Kapila Backpatch-through: 18, where it was introduced Discussion: https://postgr.es/m/canhcyexmrcedzj-rngjam0njhm4y+ttdwsgucfmxcim7bnk...@mail.gmail.com Branch -- master