pgsql: Backpatch addition of wait_for_log(), pump_until().

Backpatch addition of wait_for_log(), pump_until().

These were originally introduced in a2ab9c06ea1 and a2ab9c06ea1, as they are
needed by a about-to-be-backpatched test.

Discussion: https://postgr.es/m/20220413002626.udl7lll7f3o7nre7@alap3.anarazel.de
Backpatch: 10-14

Branch
------
REL_14_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/5ab8e8014801dd6bc05809e7ba994c013e9ee86b

Modified Files
--------------
src/test/perl/PostgreSQL/Test/Utils.pm |  1 +
src/test/perl/PostgresNode.pm          | 35 ++++++++++++++++++++++++++++++++++
src/test/perl/TestLib.pm               | 31 ++++++++++++++++++++++++++++++
3 files changed, 67 insertions(+)