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
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REL_10_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/e8a0cf9b20a12d9cb7687a1363cdeb261ef16472

Modified Files
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src/test/perl/PostgreSQL/Test/Utils.pm |  1 +
src/test/perl/PostgresNode.pm          | 36 ++++++++++++++++++++++++++++++++++
src/test/perl/TestLib.pm               | 31 +++++++++++++++++++++++++++++
3 files changed, 68 insertions(+)