pgsql: Stabilize just-added regression test cases.

Stabilize just-added regression test cases.

The tests added by commits 029dea882 et al turn out to produce
different output under -DRANDOMIZE_ALLOCATED_MEMORY.  This is
not a bug exactly: that flag causes coerce_type() to invoke
the input function twice when coercing an unknown-type literal
to a specific type.  So you get tsqueryin's bleat about an empty
tsquery twice.  Revise the test query to avoid that.

Discussion: https://postgr.es/m/20230406213813.uep7plg6lvcywujo@awork3.anarazel.de

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/5499706bdf60235f787eae9d2b541444ef0b31b3

Modified Files
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src/test/regress/expected/tsearch.out | 8 ++------
src/test/regress/sql/tsearch.sql      | 4 ++--
2 files changed, 4 insertions(+), 8 deletions(-)