MDEV-27289: mtr test for WITH_SERVER_EMBEDDED=ON reenable

mtr is checking the wrong path for the embedded executable
on out of tree builds.

The is_embedded.inc tests are also checking the version rather
than the MTR MYSQL_EMBEDDED environment variable.

As a result, a few tests are out of date in the result recordings.

mysql-test/include/is_embedded.inc

-if (`SELECT VERSION() NOT LIKE '%embedded%'`)
+if(!$MYSQL_EMBEDDED)
 {
    --skip Test requires: embedded server
 }

mysql-test/include/not_windows_embedded.inc

 let $is_win = `select convert(@@version_compile_os using latin1) IN ("Win32","Win64","Windows")`;
-let $is_embedded = `select version() like '%embedded%'`;
 #echo is_win: $is_win;
-#echo is_embedded: $is_embedded;
 if ($is_win)
 {
-  if ($is_embedded)
+  if(!$MYSQL_EMBEDDED)
   {
     skip Not supported with embedded on windows;
   }

mysql-test/mysql-test-run.pl

@@ -1968,7 +1968,7 @@ sub executable_setup () {
   $exe_mysql=          mtr_exe_exists("$path_client_bindir/mysql");
   $exe_mysql_plugin=   mtr_exe_exists("$path_client_bindir/mysql_plugin");
 
-  $exe_mysql_embedded= mtr_exe_maybe_exists("$basedir/libmysqld/examples/mysql_embedded");
+  $exe_mysql_embedded= mtr_exe_maybe_exists("$bindir/libmysqld/examples/mysql_embedded");
 
   # Look for mysqltest executable
   if ( $opt_embedded_server )

mysql-test/r/events_embedded.result

 set global event_scheduler=ON;
-ERROR HY000: Unknown system variable 'event_scheduler'
+set global event_scheduler=ORIGINAL;

mysql-test/t/events_embedded.test

 --source include/is_embedded.inc
 
---error 1193
 set global event_scheduler=ON;
+set global event_scheduler=ORIGINAL;