MDEV-35727 main.mysql-interactive fails in buildbot on debian

fix failing main.mysql-interactive

* increase socat EOF timeout from 0.5s to 10s
* add an explicit exit to not wait 10s (or even 0.5s - the test now
  finishes in 0.15s)
* enable it for libedit

mysql-test/main/mysql-interactive.result

@@ -4,6 +4,7 @@
 delimiter $
 select 1;
 $
+exit
 Welcome to the MariaDB monitor.  Commands end with ; or \g.
 Your MariaDB connection id is X
 Server version: Y
@@ -21,4 +22,5 @@ MariaDB [(none)]> select 1;
 +---+
 1 row in set
 
-MariaDB [(none)]> 
+MariaDB [(none)]> exit
+Bye