pgsql: Add more tests for VACUUM skips with partitioned tables

Add more tests for VACUUM skips with partitioned tables

A VACUUM or ANALYZE command listing directly a partitioned table expands
it to its partitions, causing all elements of a tree to be processed
with individual ownership checks done.  This results in different
relation skips depending on the ownership policy of a tree, which may
not be consistent for a partition tree.  This commit adds more tests to
ensure that any future refactoring allows to keep a consistent behavior,
or at least that any changes done are easily identified and checked.
The current behavior of VACUUM with partitioned tables is present since
10.

Author: Nathan Bossart
Reviewed-by: Michael Paquier
Discussion: https://postgr.es/m/DC186201-B01F-4A66-9EC4-F855A957C1F9@amazon.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/a569eea6998a26689409ff6eb5fce2c1eab0f5e1

Modified Files
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src/test/regress/expected/vacuum.out | 99 ++++++++++++++++++++++++++++++++++++
src/test/regress/sql/vacuum.sql      | 57 +++++++++++++++++++++
2 files changed, 156 insertions(+)