pgsql: Move test for BRIN HOT behavior to stats.sql

Move test for BRIN HOT behavior to stats.sql

The test added by 5753d4ee32 relies on statistics collector, and so it
may occasionally fail when the UDP packet gets lost. Some machines may
be susceptible to this, probably depending on load etc.

Move the test to stats.sql, which is known to already have this issue
and people know to ignore it.

Reported-by: Justin Pryzby
Discussion: https://postgr.es/m/CAFp7QwpMRGcDAQumN7onN9HjrJ3u4X3ZRXdGFT0K5G2JWvnbWg%40mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/fe60b67250a31cd1ac2a4882f12e199e30abd316

Modified Files
--------------
src/test/regress/expected/brin.out  | 51 +------------------------------------
src/test/regress/expected/stats.out | 51 +++++++++++++++++++++++++++++++++++++
src/test/regress/sql/brin.sql       | 48 +---------------------------------
src/test/regress/sql/stats.sql      | 50 ++++++++++++++++++++++++++++++++++++
4 files changed, 103 insertions(+), 97 deletions(-)