pgsql: Combine initdb tests that successfully create a data directory.

Combine initdb tests that successfully create a data directory.

This eliminates many seconds of test duration and the cause to invoke
"rm -rf", which is typically unavailable on Windows.

This is a backpatch of 1a629c1 which has never been applied to
REL9_4_STABLE.  Per complain from buildarm member drongo.

Reported-by: Tom Lane
Author: Michael Paquier, Noah Misch
Discussion: https://postgr.es/m/11800.1577060649@sss.pgh.pa.us

Branch
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REL9_4_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/297b9ccff44859f274b7408045a9c91d2bb1c6d1

Modified Files
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src/bin/initdb/t/001_initdb.pl | 48 ++++++++++++++++++------------------------
1 file changed, 20 insertions(+), 28 deletions(-)