lib/discovery: Remove some tests.

The whole lib/discovery package is being re-worked to use
"Drivers" for platform specific code and using the Go code for
actual encoding. Jungho will delete all the current lib/discovery
(BlePlugin and the likes) code shortly, but in the mean time
I'm just removing some tests that were holding up
https://vanadium-review.googlesource.com/#/c/22259/

Change-Id: I5c49a4f418610e73896f5f10d4dc1852a4013687
1 file changed