test: bluetooth: mesh_shell: Remove setting BT_MAX_CONN
test: bluetooth: mesh_shell: Remove setting BT_MAX_CONN

Only 1 connection is needed with default setting of mesh_shell.

Signed-off-by: Pavel Vasilyev <09eaab7002a868ff10244a9e1218e073869f50ea@nordicsemi.no>

galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr