MDEV-22817: Skip the test in --embedded

Author: dr-m

mysql-test/suite/parts/t/longname.test

@@ -1,5 +1,7 @@
 source include/have_innodb.inc;
 source include/have_partition.inc;
+# The absolute path names in the embedded server hit the limit earlier.
+source include/not_embedded.inc;
 set names utf8;
 
 create database mysqltest1;