pgsql: Minor cleanup related to pg_wal_replay_wait() procedure

Minor cleanup related to pg_wal_replay_wait() procedure

 * Rename $node_standby1 to $node_standby in 043_wal_replay_wait.pl as there
   is only one standby.
 * Remove useless debug printing in 043_wal_replay_wait.pl.
 * Fix typo in one check description in 043_wal_replay_wait.pl.
 * Fix some wording in comments and documentation.

Reported-by: Alexander Lakhin
Discussion: https://postgr.es/m/1d7b08f2-64a2-77fb-c666-c9a74c68eeda%40gmail.com
Reviewed-by: Alexander Lakhin

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/85b98b8d5a48092acd03db76a8bf02d9c38c1d79

Modified Files
--------------
doc/src/sgml/func.sgml                     |  2 +-
src/backend/access/transam/xlog.c          |  2 +-
src/backend/commands/waitlsn.c             |  4 +--
src/test/recovery/t/043_wal_replay_wait.pl | 48 ++++++++++++++----------------
4 files changed, 27 insertions(+), 29 deletions(-)