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_17_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/1fd6ed1f8cf5e0e40d2c66ea0ac4788af757b937

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