Separate existence of RKP VM from a specific check

Previously, two tests were combined into one. There should be a test
that checks that the RKP VM instance is declared and another test that
checks that the RKP VM DICE chain and the KeyMint DICE chain both share
the same UDS public key.

Test: atest VtsHalRemotelyProvisionedComponentTargetTest
Change-Id: I7b293ed29acd0dfaf5d96697105cc4e7ca0f6a1d