Disable EDNS for the fetchlimit test server

Disable EDNS for the fetchlimit test server

The fetchlimit test depends on a resolver continuing to try UDP
and timing out while the client waits for resolution to succeed.
but since commit bb990030 (flag day 2020), a fetch will always
switch to TCP after two timeouts, unless EDNS was disabled for
the query.

This commit adds "edns no;" to server statements in the fetchlimit
resolver, to restore the behavior expected by the test.

(cherry picked from commit 81deb24deb26095cbf3eaec8e7763973ec4177c3)