Re-Align *_freeze_max_age reloption limits with corresponding GUC limits.
Re-Align *_freeze_max_age reloption limits with corresponding GUC limits.

In 020235a5754 I lowered the autovacuum_*freeze_max_age minimums to
allow for easier testing of wraparounds. I did not touch the
corresponding per-table limits. While those don't matter for the purpose
of wraparound, it seems more consistent to lower them as well.

It's noteworthy that the previous reloption lower limit for
autovacuum_multixact_freeze_max_age was too high by one magnitude, even
before 020235a5754.

Discussion: 24af9bb9aee3dd19030f92625ce6e22106316e46@sss.pgh.pa.us
Backpatch: back to 9.0 (in parts), like the prior patch

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