Revert "support/testing: TestMdnsd: improve test reliability"

The issue was reproduced in 2026.08-rc3 Gitlab-CI pipeline [1] despite
the fix applied.

[1] https://gitlab.com/buildroot.org/buildroot/-/jobs/16185948555

This reverts commit b4b1de1f7f.

Signed-off-by: Romain Naour <romain.naour@smile.fr>
Signed-off-by: Julien Olivain <ju.o@free.fr>

support/testing/tests/package/test_mdnsd.py

@@ -1,5 +1,4 @@
 import os
-import time
 
 import infra.basetest
 
@@ -31,9 +30,6 @@ class TestMdnsd(infra.basetest.BRTest):
         # advertises the bundled _http._tcp service from /etc/mdns.d/.
         self.assertRunOk("pidof mdnsd")
 
-        # We wait for mdnsd to be ready...
-        time.sleep(1)
-
         # mdnsd only answers on multicast capable interfaces that are
         # up, so wait for eth0 to get its DHCP address before querying.
         cmd = "while ! ifconfig eth0 | grep -q 'inet addr'; do sleep 1; done"