pgsql: postgres_fdw: Revert unstable tests for postgres_fdw.application

postgres_fdw: Revert unstable tests for postgres_fdw.application_name.

Commit 6e0cb3dec1 added the tests that check that escape sequences in
postgres_fdw.application_name setting are replaced with status information
expectedly. But they were unstable and caused some buildfarm
members to report the failure. This commit reverts those unstable tests.

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/5e64ad369771b66bb3e916aade735defce6e65a1

Modified Files
--------------
contrib/postgres_fdw/expected/postgres_fdw.out | 32 --------------------------
contrib/postgres_fdw/sql/postgres_fdw.sql      | 21 -----------------
2 files changed, 53 deletions(-)