pgsql: psql: Fix tab completion for DROP INDEX CONCURRENTLY

psql: Fix tab completion for DROP INDEX CONCURRENTLY

psql offered CASCADE after DROP INDEX CONCURRENTLY and an index name,
even though CASCADE is not supported with CONCURRENTLY. Offer only
RESTRICT in this case, while retaining both CASCADE and RESTRICT
for ordinary DROP INDEX.

Backpatch to all supported versions.

Author: Sho Ito <i(dot)sho(dot)0628(at)gmail(dot)com>
Reviewed-by: Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com>
Reviewed-by: Shihao Zhong <zhong950419(at)gmail(dot)com>
Reviewed-by: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
Discussion: https://postgr.es/m/CAG7L5+7KXgvJUGCGXzyQrt7UysC9iytaYzx-7YyQTFYXjHVTWQ@mail.gmail.com
Backpatch-through: 14

Branch
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REL_16_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/0d8bfc5e3663ae5a6d1ae4e4316cdaa8480e168e

Modified Files
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src/bin/psql/tab-complete.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)