pgsql: Add missing COSTS OFF to EXPLAIN commands in rowsecurity.sql.

Add missing COSTS OFF to EXPLAIN commands in rowsecurity.sql.

Commit e5e11c8cc added a bunch of EXPLAIN statements without COSTS OFF
to the regression tests.  This is contrary to project policy since it
results in unnecessary platform dependencies in the output (it's just
luck that we didn't get buildfarm failures from it).  Per gripe from
Mike Wilson.

Branch
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REL9_5_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/3ef762e7d806f18db743fd10bbf75a9b2631033c

Modified Files
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src/test/regress/expected/rowsecurity.out |  184 ++++++++++++++---------------
src/test/regress/sql/rowsecurity.sql      |   24 ++--
2 files changed, 104 insertions(+), 104 deletions(-)