Bluetooth: tests: shell: Remove config not supported on native_posix

Remove CONFIG_CONSOLE_HANDLER from project configuration. When building
for native_posix this produces the following warning:

warning: CONSOLE_HANDLER was assigned the value 'y' but gotthe value 'n'
Check these unsatisfied dependencies: SERIAL_SUPPORT_INTERRUPT (=n)

The shell works without this option since this is handled by the shell
itself instead.

Signed-off-by: Joakim Andersson <joakim.andersson@nordicsemi.no>