logd: use the compressed (serialized) log buffer by default

The serialized log buffer along with compression results in:
* ~3.5x more logs than chatty
* Less CPU usage
* Less memory usage
* Equivalent log range

Also, delete tests that assume that the device logd implementation is
chatty.  There are actual unit tests for this same behavior that don't
rely on the device logd.

Test: serialized log buffer is used
Change-Id: Ie12898617429a75b6caff92725aa7145650f8fc6