Keystore 2.0: Remove attestKey from KeyChain.

KeyChain supports device id attestation through KeyGenParameterSpec now.
No need to call attest key individually. Also calling attest key
individually is no longer supported by Keystore 2.0 and KeyMint.

Also isBoundKeyAlgorithm returns true.

Test: atest FrameworksServicesTests:DevicePolicyManagerTest
Bug: 171305387
Change-Id: I759fe245b48fe435153fded2c74c9ae99634c146