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_18_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/5b5c68194c545217b10582b92a6f89c70185c1db

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