pgsql: vacuumdb: Fix excluding multiple schemas with -N

vacuumdb: Fix excluding multiple schemas with -N

When specifying multiple schemas to exclude with -N parameters, none
of the schemas are actually excluded (a single -N worked as expected).
This fixes the catalog query to handle multiple exclusions and adds a
test for this case.

Backpatch to v16 where this was introduced.

Author: Nathan Bossart <nathandbossart(at)gmail(dot)com>
Author: Kuwamura Masaki <kuwamura(at)db(dot)is(dot)i(dot)nagoya-u(dot)ac(dot)jp>
Reported-by: Kuwamura Masaki <kuwamura(at)db(dot)is(dot)i(dot)nagoya-u(dot)ac(dot)jp>
Discussion: https://postgr.es/m/CAMyC8qp9mXPQd5D6s6CJxvmignsbTqGZwDDB6VYJOn1A8WG38w@mail.gmail.com
Backpatch-through: 16

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/fb56a181175bba03a6d4f82cd3c07ec5511ce545

Modified Files
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src/bin/scripts/t/100_vacuumdb.pl | 15 ++++++++++++++-
src/bin/scripts/vacuumdb.c | 26 ++++++++++++++++----------
2 files changed, 30 insertions(+), 11 deletions(-)