Enlarge assertion in bloom_init() for false_positive_rate

Enlarge assertion in bloom_init() for false_positive_rate

false_positive_rate is a parameter that can be set with the bloom
opclass in BRIN, and setting it to a value of exactly 0.25 would trigger
an assertion in the first INSERT done on the index with value set.

The assertion changed here relied on BLOOM_{MIN|MAX}_FALSE_POSITIVE_RATE
that are somewhat arbitrary values, and specifying an out-of-range value
would also trigger a failure when defining such an index.  So, as-is,
the assertion was just doubling on the min-max check of the reloption.
This is now enlarged to check that it is a correct percentage value,
instead, based on a suggestion by Tom Lane.

Author: Alexander Lakhin
Reviewed-by: Tom Lane, Shihao Zhong
Discussion: https://postgr.es/m/17969-a6c54de48026d694@postgresql.org
Backpatch-through: 14