BassClient: Fix not clearing pending op. metadata

Pending metadata should be cleared when leaving the
ConnectedProcessing state, otherwise we would reject
other operations after the first operation times out
and throw IllegalStateException.

Bug: 150670922
Test: manually tested
Sponsor: jpawlowski@
Merged-In: Ie018fe0925b2f4580460b0f52b959ce21f3ad153
Change-Id: Ie018fe0925b2f4580460b0f52b959ce21f3ad153
(cherry picked from commit 82429cb1)