pgsql: Preparatory test cleanup - Mailing list pgsql-committers

Preparatory test cleanup

Add a little bit of explanation, clarity, and space.  Extraced from a
larger patch so that the changes from that patch would be easier to
identify.

Discussion: https://www.postgresql.org/message-id/flat/04e12818-2f98-257c-b926-2845d74ed04f%402ndquadrant.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/ae63017bdb316b16a9f201b10f1221598111d6c5

Modified Files
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src/test/regress/expected/alter_table.out | 76 +++++++++++++++----------------
src/test/regress/sql/alter_table.sql      | 21 +++++----
2 files changed, 49 insertions(+), 48 deletions(-)