tests: bluetooth/mesh_shell: Fine-tune config for lower RAM footprint

This app was supposed to have userspace disabled, but it kept on being
forced on by CONFIG_TEST_USERSPACE (which in turn gets enabled by
CONFIG_TEST).

Also lower the shell stack size since stack analysis shows over 700
bytes being unused.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
1 file changed