ENYO-468: Remove conditional related to falsy locale.

### Issue
When switching between multiple samples in Sampler, the locale was not being reset.

### Fix
`ilib` had recently made a change to support the setting of `null` values for the locale, which would set the locale to "local" by default. This eliminates the need for the conditional when initializing `moon.DateTimePickerBase` as the default value of locale is `null`, which will appropriately set the locale. Additionally, there is some clean-up for the use of the `iLibLocale` var.

Enyo-DCO-1.1-Signed-off-by: Aaron Tam <aaron.tam@lge.com>