pgsql: Move some code from RewindTest into PostgresNode

Move some code from RewindTest into PostgresNode

Some code in the RewindTest test suite is more generally useful than
just for that suite, so put it where other test suites can reach it.

Some postgresql.conf parameters change their default values when a
cluster is initialized with 'allows_streaming' than the previous
behavior; most notably, autovacuum is no longer turned off.

(Also, we no longer call pg_ctl promote with -w, but that flag doesn't
actually do anything in promote so there's no behavior change.)

Author: Michael Paquier

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/89ac7004dadf4116d9b180bb5ff64b64bfce94b1

Modified Files
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src/bin/pg_rewind/RewindTest.pm | 19 ++---------
src/test/perl/PostgresNode.pm | 71 ++++++++++++++++++++++++++++++++++++-----
2 files changed, 65 insertions(+), 25 deletions(-)