[Pandora] - Simulate CSR command timeout

Introducing a 2s sleep at the beggining of the avrcp tests to Simulate
the previous non implemented rootcanal command vendor.

The CSR vendor command was not implemented and timed out at the
beggining of each HFP tests. Since they are implemented in rootcanal,
the timeout doesn't exists and the tests are failing.
Bug: 245578454
Test: atests pts-bot:AVRCP -v
Ignore-AOSP-First: Cherry-picked from AOSP
Merged-In: I6838149dd1f34477f48df3ae767656a29a4aa678
Change-Id: I6838149dd1f34477f48df3ae767656a29a4aa678