pgsql: Remove unwarranted Assert in dependencies_clauselist_selectivity

Remove unwarranted Assert in dependencies_clauselist_selectivity()

The loop above from where the Assert is removed handles assigning the same
attnum to any duplicate expressions, so asserting there are no duplicate
attnums just after purposefully making duplicate ones isn't the correct
thing to do.

The Assert was added by a4d75c86bf, so backpatch to v14

Author: BHUVAN CHILUKUTI <c(dot)bhuvan(at)iitg(dot)ac(dot)in>
Reviewed-by: David Rowley <dgrowleyml(at)gmail(dot)com>
Discussion: https://postgr.es/m/PN0P287MB0903563C70D8E5B81912E855A7602@PN0P287MB0903.INDP287.PROD.OUTLOOK.COM
Backpatch-through: 14

Branch
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REL_15_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/d4a81ec05ee1bc197c780092e8cc2b41ff7fcbd9

Modified Files
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src/backend/statistics/dependencies.c | 11 -----------
1 file changed, 11 deletions(-)