BUG#49978: Replication tests don't clean up replication state at the end

Major replication test framework cleanup. This does the following:
 - Ensure that all tests clean up the replication state when they
   finish, by making check-testcase check the output of SHOW SLAVE STATUS.
   This implies:
    - Slave must not be running after test finished. This is good
      because it removes the risk for sporadic errors in subsequent
      tests when a test forgets to sync correctly.
    - Slave SQL and IO errors must be cleared when test ends. This is
      good because we will notice if a test gets an unexpected error in
      the slave threads near the end.
    - We no longer have to clean up before a test starts.
 - Ensure that all tests that wait for an error in one of the slave
   threads waits for a specific error. It is no longer possible to
   source wait_for_slave_[sql|io]_to_stop.inc when there is an error
   in one of the slave threads. This is good because:
    - If a test expects an error but there is a bug that causes
      another error to happen, or if it stops the slave thread without
      an error, then we will notice.
    - When developing tests, wait_for_*_to_[start|stop].inc will fail
      immediately if there is an error in the relevant slave thread.
      Before this patch, we had to wait for the timeout.
 - Remove duplicated and repeated code for setting up unusual replication
   topologies. Now, there is a single file that is capable of setting
   up arbitrary topologies (include/rpl_init.inc, but
   include/master-slave.inc is still available for the most common
   topology). Tests can now end with include/rpl_end.inc, which will clean
   up correctly no matter what topology is used. The topology can be
   changed with include/rpl_change_topology.inc.
 - Improved debug information when tests fail. This includes:
    - debug info is printed on all servers configured by include/rpl_init.inc
    - User can set $rpl_debug=1, which makes auxiliary replication files
      print relevant debug info.
 - Improved documentation for all auxiliary replication files. Now they
   describe purpose, usage, parameters, and side effects.
 - Many small code cleanups:
    - Made have_innodb.inc output a sensible error message.
    - Moved contents of rpl000017-slave.sh into rpl000017.test
    - Added mysqltest variables that expose the current state of
      disable_warnings/enable_warnings and friends.
    - Too many to list here: see per-file comments for details.

mysql-test/suite/rpl/r/rpl_slave_grp_exec.result

@@ -1,9 +1,5 @@
-stop slave;
-drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
-reset master;
-reset slave;
-drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
-start slave;
+include/master-slave.inc
+[connection master]
 
 *** Preparing data ***
 CREATE TABLE t1 (a INT NOT NULL, b VARCHAR(10)) ENGINE=MyISAM;
@@ -33,6 +29,7 @@ a	b
 SELECT * FROM t3 ORDER BY a;
 a	b
 1	ZZ
+include/wait_for_slave_sql_error.inc [errno=1146]
 SHOW TABLES LIKE 't%';
 Tables_in_test (t%)
 t1
@@ -44,7 +41,7 @@ a	b
 SELECT * FROM t2 ORDER BY a;
 a	b
 1	AA_for_row_or_YY_for_stmt_mixed
-include/stop_slave.inc
+include/stop_slave_io.inc
 RENAME TABLE t3_bak TO t3;
 include/start_slave.inc
 TRUNCATE t1;
@@ -60,6 +57,7 @@ INSERT INTO t3 VALUES(2, 'B');
 INSERT INTO t2 VALUES(2, 'B');
 INSERT INTO t1 VALUES(2, 'B');
 UPDATE t1 SET b = 'X' WHERE a = 2;
+include/wait_for_slave_sql_error.inc [errno=1146]
 SELECT * FROM t1 ORDER BY a;
 a	b
 2	X
@@ -78,7 +76,7 @@ SELECT * FROM t1 ORDER BY a;
 a	b
 SELECT * FROM t2 ORDER BY a;
 a	b
-include/stop_slave.inc
+include/stop_slave_io.inc
 RENAME TABLE t3_bak TO t3;
 include/start_slave.inc
 TRUNCATE t1;
@@ -95,6 +93,7 @@ INSERT INTO t1 VALUES (3, 'C'), (4, 'D');
 INSERT INTO t2 VALUES (3, 'C'), (4, 'D');
 INSERT INTO t3 VALUES (3, 'C'), (4, 'D');
 COMMIT;
+include/wait_for_slave_sql_error.inc [errno=1146]
 SELECT * FROM t1 ORDER BY a;
 a	b
 3	C
@@ -116,8 +115,9 @@ SELECT * FROM t1 ORDER BY a;
 a	b
 SELECT * FROM t2 ORDER BY a;
 a	b
-include/stop_slave.inc
+include/stop_slave_io.inc
 RENAME TABLE t3_bak TO t3;
 include/start_slave.inc
 *** Clean up ***
 DROP TABLE t1,t2,t3;
+include/rpl_end.inc