Remove 'asynchronously_start_l2cap_coc' flag since it has been enabled in prod...

Remove 'asynchronously_start_l2cap_coc' flag since it has been enabled in prod bug-free since tm-qpr2-release.

Bug: 290842781
Tag: #stability
Test: m -j $(nproc) ; Android should build without the flag as well.
Change-Id: I43293d3c7c45c2aab0e7c29304b86045b727ffb4