Use bluetooth-specific statslog

Use generated statslog_bt that contains a subset of stats_write methods
only required for bluetooth module. This replaces monolithic libstatslog.
There's currently a stats_write method signature collision with another atom
(b/200741446). This fixes the collision by only linking against
stats_write() methods needed for atoms with the 'bluetooth' module
annotation.

Bug: 200741446
Tag: #refactor
Test: atest net_test_btif
Test: atest net_test_btif_profile_queue
Test: gd/cert/run
Test: m libbtif
Test: m libbluetooth
Test: m bt_headless
Test: m libstatslog_bt
Test: m
Change-Id: I4323117ddcdd344e2dcf15a7631e2dec37f0b38f