pgsql: Fix cross-version upgrades with XMLSERIALIZE(NO INDENT)

Fix cross-version upgrades with XMLSERIALIZE(NO INDENT)

Dumps from versions older than v16 do not know about NO INDENT in a
XMLSERIALIZE() clause. This commit adjusts AdjustUpgrade.pm so as NO
INDENT is discarded in the contents of the new dump adjusted for
comparison when the old version is v15 or older. This should be enough
to make the cross-version upgrade tests pass.

Per report from buildfarm member crake. Oversight in 984410b92326.

Reviewed-by: Andrew Dunstan <andrew(at)dunslane(dot)net>
Discussion: https://postgr.es/m/88b183f1-ebf9-4f51-9144-3704380ccae7@dunslane.net
Backpatch-through: 16

Branch
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REL_16_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/514d47dfb69caec14b62b294f899b2e953cc2baa

Modified Files
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src/test/perl/PostgreSQL/Test/AdjustUpgrade.pm | 6 ++++++
1 file changed, 6 insertions(+)