Audio HAL: Fix UAF if the effect is removed after close

Effect::close in V6 releases the underlying HAL effect.
It was not removing the effect entry from the effects
map, thus a call to Stream::removeEffect was retrieving
a stale handle.

Bug: 145656878
Test: start and stop recording for VOICE_COMMUNICATION
Change-Id: I47f486d3b6b4b0dc29acd1e3a2093e421b28d90b