pgsql: Suppress DROP CASCADE notices in regression tests

Suppress DROP CASCADE notices in regression tests

In the regression tests, when doing cascaded drops, we need to suppress
the notices from DROP CASCADE or there can be transient regression
failures as the order of drops can depend on the physical row order in
pg_depend.

Report and fix suggestion from Tom.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/81d815dc3ed74a7d20f7b4c7d87c42816c7ee7af

Modified Files
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src/test/regress/expected/rowsecurity.out |   40 +++++++----------------------
src/test/regress/sql/rowsecurity.sql      |   14 ++++++++++
2 files changed, 23 insertions(+), 31 deletions(-)