pgsql: Improve test coverage in bump.c

Improve test coverage in bump.c

There were no callers of BumpAllocLarge() in the regression tests, so
here we add a sort with a tuple large enough to use that path in bump.c.

Also, BumpStats() wasn't being called, so add a test to sysviews.sql to
call pg_backend_memory_contexts() while a bump context exists in the
backend.

Reported-by: Andres Freund
Discussion: https://postgr.es/m/20240414223305.m3i5eju6zylabvln@awork3.anarazel.de

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/bea97cd02ebb347ab469b78673c2b33a72109669

Modified Files
--------------
src/test/regress/expected/sysviews.out | 23 +++++++++++++++++++++++
src/test/regress/expected/tuplesort.out | 13 +++++++++++++
src/test/regress/sql/sysviews.sql | 15 +++++++++++++++
src/test/regress/sql/tuplesort.sql | 9 +++++++++
4 files changed, 60 insertions(+)