sample: subsys: shell: shell_module: add config for timing at boot

Use of CONFIG_THREAD_RUNTIME_STATS was added to this sample, but
caused issue because the call to z_thread_mark_switched_in()
is using k_cycle_get_32() before the timer is initialized.
Enable CONFIG_THREAD_RUNTIME_STATS_USE_TIMING_FUNCTIONS=y to
select hidden config CONFIG_TIMING_FUNCTIONS_NEED_AT_BOOT,
which calls to initialize the timer needed at boot for thread
runtime stats configuration.

Fixes #33275

Signed-off-by: Jennifer Williams <jennifer.m.williams@intel.com>