MDEV-30269: Remove rpl_semi_sync_[slave,master] usage in code

- Description:
  - Before 10.3.8 semisync was a plugin that is built into the server with
    MDEV-13073,starting with commit cbc71485e24c31fc822277625512e55c2a8b650b.
    There are still some usage of `rpl_semi_sync_master` in mtr.
Note:
  - To recognize the replica in the `dump_thread`, replica is creating
    local variable `rpl_semi_sync_slave` (the keyword of plugin) in
    function `request_transmit`, that is catched by primary in
    `is_semi_sync_slave()`. This is the user variable and as such not
    related to the obsolete plugin.

 - Found in `sys_vars.all_vars` and `rpl_semi_sync_wait_point` tests,
   usage of plugins `rpl_semi_sync_master`, `rpl_semi_sync_slave`.
   The former test is disabled by default (`sys_vars/disabled.def`)
   and marked as `obsolete`, however this patch will remove the queries.

- Add cosmetic fixes to semisync codebase

Reviewer: <brandon.nesterenko@mariadb.com>
Closes PR #2528, PR #2380

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

@@ -7,8 +7,6 @@ SET @@global.rpl_semi_sync_master_timeout = 60000;
 SET @@global.rpl_semi_sync_master_wait_no_slave = 1;
 # It's okay to see "Killed" but we should not see "Timeout" in the log.
 call mtr.add_suppression("Killed waiting for reply of binlog");
-call mtr.add_suppression("Run function 'after_commit' in plugin 'rpl_semi_sync_master' failed");
-call mtr.add_suppression("Run function 'after_sync' in plugin 'rpl_semi_sync_master' failed");
 #
 # Test wait point = AFTER_COMMIT
 #

mysql-test/suite/rpl/t/rpl_semi_sync_wait_point.test

@@ -23,8 +23,6 @@ SET @@global.rpl_semi_sync_master_wait_no_slave = 1;
 
 --echo # It's okay to see "Killed" but we should not see "Timeout" in the log.
 call mtr.add_suppression("Killed waiting for reply of binlog");
-call mtr.add_suppression("Run function 'after_commit' in plugin 'rpl_semi_sync_master' failed");
-call mtr.add_suppression("Run function 'after_sync' in plugin 'rpl_semi_sync_master' failed");
 
 --echo #
 --echo # Test wait point = AFTER_COMMIT

mysql-test/suite/sys_vars/t/all_vars.test

@@ -13,8 +13,6 @@ eval INSTALL PLUGIN federated SONAME "$HA_FEDERATEDX_SO";
 eval INSTALL PLUGIN oqgraph SONAME "$HA_OQGRAPH_SO";
 eval INSTALL PLUGIN sphinx SONAME "$HA_SPHINX_SO";
 eval INSTALL PLUGIN innodb SONAME "$HA_INNODB_SO";
-eval INSTALL PLUGIN rpl_semi_sync_master SONAME "$SEMISYNC_MASTER_SO";
-eval INSTALL PLUGIN rpl_semi_sync_slave SONAME "$SEMISYNC_SLAVE_SO";
 --enable_abort_on_error
 --enable_result_log
 --enable_query_log

sql/semisync_master.cc

@@ -317,8 +317,8 @@ void Active_tranx::clear_active_tranx_nodes(const char *log_file_name,
 
 /*******************************************************************************
  *
- * <Repl_semi_sync_master> class: the basic code layer for syncsync master.
- * <Repl_semi_sync_slave>  class: the basic code layer for syncsync slave.
+ * <Repl_semi_sync_master> class: the basic code layer for semisync master.
+ * <Repl_semi_sync_slave>  class: the basic code layer for semisync slave.
  *
  * The most important functions during semi-syn replication listed:
  *
@@ -809,8 +809,6 @@ void Repl_semi_sync_master::dump_end(THD* thd)
 
   remove_slave();
   ack_receiver.remove_slave(thd);
-
-  return;
 }
 
 int Repl_semi_sync_master::commit_trx(const char* trx_wait_binlog_name,

sql/sql_repl.cc

@@ -433,7 +433,7 @@ static int send_file(THD *thd)
 
 /**
    Internal to mysql_binlog_send() routine that recalculates checksum for
-   1. FD event (asserted) that needs additional arranment prior sending to slave.
+   1. FD event (asserted) that needs additional arrangement prior sending to slave.
    2. Start_encryption_log_event whose Ignored flag is set
 TODO DBUG_ASSERT can be removed if this function is used for more general cases
 */