Clean up duplicate table and function names in regression tests.

Many of the objects we create during the regression tests are put in the
public schema, so that using the same names in different regression tests
creates a hazard of test failures if any two such scripts run concurrently.
This patch cleans up a bunch of latent hazards of that sort, as well as two
live hazards.

The current situation in this regard is far worse than it was a year or two
back, because practically all of the partitioning-related test cases have
reused table names with enthusiasm.  I despaired of cleaning up that mess
within the five most-affected tests (create_table, alter_table, insert,
update, inherit); fortunately those don't run concurrently.

Other than partitioning problems, most of the issues boil down to using
names like "foo", "bar", "tmp", etc, without thought for the fact that
other test scripts might use similar names concurrently.  I've made an
effort to make all such names more specific.

One of the live hazards was that commit 7421f4b caused with.sql to
create a table named "test", conflicting with a similarly-named table
in alter_table.sql; this was exposed in the buildfarm recently.
The other one was that join.sql and transactions.sql both create tables
named "foo" and "bar"; but join.sql's uses of those names date back
only to December or so.

Since commit 7421f4b was back-patched to v10, back-patch a minimal
fix for that problem.  The rest of this is just future-proofing.

Discussion: https://postgr.es/m/4627.1521070268@sss.pgh.pa.us

Author: tglsfdc

src/test/regress/expected/alter_table.out

@@ -8,7 +8,7 @@ ERROR:  random() is not a procedure
 LINE 1: CALL random();
              ^
 HINT:  To call a function, use SELECT.
-CREATE FUNCTION testfunc1(a int) RETURNS int LANGUAGE SQL AS $$ SELECT a $$;
+CREATE FUNCTION cp_testfunc1(a int) RETURNS int LANGUAGE SQL AS $$ SELECT a $$;
 CREATE TABLE cp_test (a int, b text);
 CREATE PROCEDURE ptest1(x text)
 LANGUAGE SQL
@@ -118,14 +118,14 @@ LINE 1: ALTER PROCEDURE ptest1(text) STRICT;
                                      ^
 ALTER FUNCTION ptest1(text) VOLATILE;  -- error: not a function
 ERROR:  ptest1(text) is not a function
-ALTER PROCEDURE testfunc1(int) VOLATILE;  -- error: not a procedure
-ERROR:  testfunc1(integer) is not a procedure
+ALTER PROCEDURE cp_testfunc1(int) VOLATILE;  -- error: not a procedure
+ERROR:  cp_testfunc1(integer) is not a procedure
 ALTER PROCEDURE nonexistent() VOLATILE;
 ERROR:  procedure nonexistent() does not exist
 DROP FUNCTION ptest1(text);  -- error: not a function
 ERROR:  ptest1(text) is not a function
-DROP PROCEDURE testfunc1(int);  -- error: not a procedure
-ERROR:  testfunc1(integer) is not a procedure
+DROP PROCEDURE cp_testfunc1(int);  -- error: not a procedure
+ERROR:  cp_testfunc1(integer) is not a procedure
 DROP PROCEDURE nonexistent();
 ERROR:  procedure nonexistent() does not exist
 -- privileges
@@ -141,11 +141,11 @@ SET ROLE regress_cp_user1;
 CALL ptest1('a');  -- ok
 RESET ROLE;
 -- ROUTINE syntax
-ALTER ROUTINE testfunc1(int) RENAME TO testfunc1a;
-ALTER ROUTINE testfunc1a RENAME TO testfunc1;
+ALTER ROUTINE cp_testfunc1(int) RENAME TO cp_testfunc1a;
+ALTER ROUTINE cp_testfunc1a RENAME TO cp_testfunc1;
 ALTER ROUTINE ptest1(text) RENAME TO ptest1a;
 ALTER ROUTINE ptest1a RENAME TO ptest1;
-DROP ROUTINE testfunc1(int);
+DROP ROUTINE cp_testfunc1(int);
 -- cleanup
 DROP PROCEDURE ptest1;
 DROP PROCEDURE ptest2;