Prior to this change, recompilation of AOT-compiled components in TestBed may fail when template override is requested. That was happening due to the `styleUrls` field defined for a Component, thus switching its state to "requires resolution" (i.e. having external resources) at compile time. This change avoids this issue by storing styles and resetting `styleUrls` field before recompilation. Once compilation is done, saved styles are patched back onto Component def.
PR Close#29555