MAINTAINERS: move mesh and ll from bsim/tests to their proper section

The babblesim tests for bluetooth have been moved to a new folder.
To ensure that the proper people still get involved this PR adds
the bsim/tests/bluetooth/ll folder to the bluetooth controller section
and similar for the mesh babblesim folder

Signed-off-by: Andries Kruithof <andries.kruithof@nordicsemi.no>