pgsql: When VACUUM or ANALYZE skips a concurrently dropped table,log i

When VACUUM or ANALYZE skips a concurrently dropped table, log it.

Hopefully, the additional logging will help avoid confusion that
could otherwise result.

Nathan Bossart, reviewed by Michael Paquier, Fabrízio Mello, and me

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/ab6eaee88420db58a948849d5a735997728d73a9

Modified Files
--------------
doc/src/sgml/config.sgml                           |  4 +-
src/backend/commands/analyze.c                     | 46 +++++++++++--
src/backend/commands/vacuum.c                      | 49 ++++++++++++--
.../isolation/expected/vacuum-concurrent-drop.out  | 76 ++++++++++++++++++++++
src/test/isolation/isolation_schedule              |  1 +
.../isolation/specs/vacuum-concurrent-drop.spec    | 45 +++++++++++++
6 files changed, 208 insertions(+), 13 deletions(-)