pgsql: Fix typos and grammar in code and test comments

Fix typos and grammar in code and test comments

This fixes the grammar of some comments in a couple of tests (SQL and
TAP), and in some C files.

Author: Justin Pryzby
Discussion: https://postgr.es/m/20220511020334.GH19626@telsasoft.com

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/45edde037efc6ec76714e0be7309b348fe34351e

Modified Files
--------------
contrib/citext/expected/citext.out          | 2 +-
contrib/citext/expected/citext_1.out        | 2 +-
contrib/citext/sql/citext.sql               | 2 +-
src/backend/executor/execGrouping.c         | 2 +-
src/backend/parser/parse_expr.c             | 2 +-
src/backend/replication/basebackup_target.c | 2 +-
src/bin/pg_basebackup/bbstreamer_tar.c      | 2 +-
src/bin/pg_rewind/t/007_standby_source.pl   | 2 +-
src/bin/pg_rewind/t/009_growing_files.pl    | 2 +-
src/test/regress/expected/psql.out          | 2 +-
src/test/regress/sql/psql.sql               | 2 +-
src/test/ssl/t/SSL/Backend/OpenSSL.pm       | 2 +-
12 files changed, 12 insertions(+), 12 deletions(-)