pgsql: Fix test_rls_hooks to assign expression collations properly.

Fix test_rls_hooks to assign expression collations properly.

This module overlooked this necessary fixup step on the results of
transformWhereClause().  It accidentally worked anyway, because the
constructed expression involved type "name" which is not collatable,
but it fell over while I was experimenting with changing "name" to
be collatable.

Back-patch, not because there's any live bug here in back branches,
but because somebody might use this code as a model for some real
application and then not understand why it doesn't work.

Branch
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REL_10_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/0226cd72ec46ae946db77e9904b5588ca54f3ec6

Modified Files
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src/test/modules/test_rls_hooks/test_rls_hooks.c | 5 +++++
1 file changed, 5 insertions(+)