Summary:
A failing check_ctags in postgres.sh only printed an install hint to
stderr while the script carried on, so the ctags rules missing_yb_prefix
and missing_yb_typedef checked nothing and the lint drivers reported the
file clean.  Exit 1 like typedefs_list.sh does so the drivers surface a
linter failure instead.

Test Plan:
Put a fake ctags first on PATH that answers --version with "Universal
Ctags 6.0" and fails any other invocation, then run postgres.sh on
nodeYbSeqscan.c with an unmarked typedef injected.  Before this change
it exits 0 with no findings, after it exits 1, which both arc lint and
build-support/lint.py report as a linter failure.

With Exuberant Ctags restored, the injected typedef draws
missing_yb_prefix as before, and an unmodified file lints clean with
exit 0.

Close: #33441
Jenkins: skip

Reviewers: patnaik.balivada

Reviewed By: patnaik.balivada

Differential Revision: https://phorge.dev.yugabyte.com/D57242