Remove `test_mdns_via_hotspot` multi-devices test

This test added from CTS-15_r2, new test cases should be punted to CTS-16 release.

Bug: 368983928
Test: test-only change
Merged-In: I9f52a271385cddc12c8f57b188e080ad69651f9f
Change-Id: Ifb8c47ec4bca16f21a77a8da64ab6e4c874d15fd
1 file changed