pgsql: Revert "In the pg_upgrade test suite,don't write to src/test/re

Revert "In the pg_upgrade test suite, don't write to src/test/regress."

This reverts commit bd1592e8570282b1650af6b8eede0016496daecd.  It had
multiple defects.

Discussion: https://postgr.es/m/12717.1558304356@sss.pgh.pa.us

Branch
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REL9_5_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/2604751c73e59a1dd148361345b643676c9e4110

Modified Files
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src/bin/pg_upgrade/test.sh                   | 12 ------------
src/test/regress/input/largeobject.source    |  6 +++---
src/test/regress/output/largeobject.source   |  6 +++---
src/test/regress/output/largeobject_1.source |  6 +++---
src/tools/msvc/vcregress.pl                  | 18 +-----------------
5 files changed, 10 insertions(+), 38 deletions(-)