parse ON UPDATE / ON DELETE in any order

parse ON UPDATE / ON DELETE in any order

Fixed an issue in the PostgreSQL dialect where foreign key constraint
reflection would incorrectly swap or fail to capture ``onupdate`` and
``ondelete`` values when these clauses appeared in a different order than
expected in the constraint definition. This issue primarily affected
PostgreSQL-compatible databases such as CockroachDB, which may return ``ON
DELETE`` before ``ON UPDATE`` in the constraint definition string. The
reflection logic now correctly parses both clauses regardless of their
ordering.

Fixes: #13105
Change-Id: I1331b433f713632e84ae6a34467806e080b8003e