Test the format of patch level device info

On top of checking that the patch level are a UINT, also check that they
follow the YYYYMM or YYYYMMDD format in the CSR v3 as is required by the
server validation logic. This check is not applied in the factory as the
value might not yet be correctly provisioned.

Bug: 269813991
Test: atest VtsHalRemotelyProvisionedComponentTargetTest
Change-Id: I5c62ba176dae390ea0a387bba6cb975226e3873a