Due to a limitation in the west import feature,
a project cannot both have an import and be part of a group.
Moreover, when a project has an import and is not filtered
out, it is required for that project to be present
for most west commands to work.

As the bsim project is not filtered by default,
it causes trouble for users who never run a
west update but try to use west further.

To work around this issue, let's disable the import
in the bsim project, and instead import the
manifest from a local replica int his repository.

Having a replica of the babblesim manifes
is likely to cause some confusion in users,
wrt to which version of components they are using.
So whenever west supports both imports and groups, or another
simple and nicer way of working around this, it should be used.

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>

This reverts commit 00130b7.

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>

As the bsim repo is disabled by default, west list bsim -f {sha}
fails.
Instead get the revision field which works.

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>