CODEOWNERS: Remove aescolar from tests/bluetooth/bsim_bt/

Practically all changes in the last 2 years in this folder
are in actual tests, and not in infrastructure.
There is no need for me to be added as reviewer to them,
specially as all involved know how to ping me if needed.
=> Remove myself from the CODEOWNERS list for
tests/bluetooth/bsim_bt/

Signed-off-by: Alberto Escolar Piedras <alpi@oticon.com>