Camera VTS: Properly initialize Stream in various places

useCase and colorSpace are not explicitly initialized. colorSpace must
be explicitly initialized to UNSPECIFIED, as its default value is not
zero. Without initialization, the HAL will receive incorrect Stream
data.

Bug: 287305593
Test: Ran full VTS test on Cuttlefish / OEM testing.
Change-Id: I6a29600b5dc06ebdc61b38e0585204fe52d590c2