Address vtpm_live_migration parameter downstream

Downstream is currently running tempest 46.0.0 which does not yet have access to vtpm_live_migration [1]. Without that reference, whitebox tests fail to properly load when evaluating the related skipChecks. As a temporary workaround to address issues downstream, creating config parameter vtpm_live_migration_supported within the whitebox repo to serve as vtpm_live_migration until it is available downstream.

This parameter and skipcheck change will be reverted when [1] lands downstream.