Add test where trusted old key can continue to update package

When a key is rotated by a new key, the new key may continue trusting
the old key. In such case, the old key should be able to update the
package.

Bug: 136002636
Test: atest StagedInstallTest#testTrustedOldKeyIsAccepted
Test: atest CtsStagedInstallHostTestCases
Test: atest CtsRollbackManagerHostTestCases
Change-Id: I134ad44d5928a408f81e4d82a776f9a3497b8140
5 files changed