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.

contrib/postgres_fdw/expected/postgres_fdw.out

@@ -10825,35 +10825,3 @@ ERROR:  invalid value for integer option "batch_size": 100$%$#$#
 ALTER FOREIGN DATA WRAPPER postgres_fdw OPTIONS (nonexistent 'fdw');
 ERROR:  invalid option "nonexistent"
 HINT:  There are no valid options in this context.
--- ===================================================================
--- test postgres_fdw.application_name GUC
--- ===================================================================
--- Close all the existing cached connections so that new connection
--- will be established with new setting of postgres_fdw.application_name.
-SELECT 1 FROM postgres_fdw_disconnect_all();
- ?column? 
-----------
-        1
-(1 row)
-
--- Add some escape sequences into postgres_fdw.application_name
--- so as to test that they are replaced with status information expectedly.
-SET postgres_fdw.application_name TO '%a%u%d%p%%';
-BEGIN;
-SELECT 1 FROM ft6 LIMIT 1;
- ?column? 
-----------
-        1
-(1 row)
-
-SELECT count(*) FROM pg_stat_activity
-  WHERE application_name = current_setting('application_name') ||
-    CURRENT_USER || current_database() || pg_backend_pid() || '%';
- count 
--------
-     1
-(1 row)
-
-COMMIT;
---Clean up
-RESET postgres_fdw.application_name;

contrib/postgres_fdw/sql/postgres_fdw.sql

@@ -3452,24 +3452,3 @@ CREATE FOREIGN TABLE inv_bsz (c1 int )
 
 -- No option is allowed to be specified at foreign data wrapper level
 ALTER FOREIGN DATA WRAPPER postgres_fdw OPTIONS (nonexistent 'fdw');
-
--- ===================================================================
--- test postgres_fdw.application_name GUC
--- ===================================================================
--- Close all the existing cached connections so that new connection
--- will be established with new setting of postgres_fdw.application_name.
-SELECT 1 FROM postgres_fdw_disconnect_all();
-
--- Add some escape sequences into postgres_fdw.application_name
--- so as to test that they are replaced with status information expectedly.
-SET postgres_fdw.application_name TO '%a%u%d%p%%';
-
-BEGIN;
-SELECT 1 FROM ft6 LIMIT 1;
-SELECT count(*) FROM pg_stat_activity
-  WHERE application_name = current_setting('application_name') ||
-    CURRENT_USER || current_database() || pg_backend_pid() || '%';
-COMMIT;
-
---Clean up
-RESET postgres_fdw.application_name;