The forge keybox selector matched the requested algorithm exactly and
threw -75 ATTESTATION_KEYS_NOT_PROVISIONED on a miss, while the patch
path already falls back to any usable key (EC preferred). An RSA
ATTEST_KEY request on an EC-only keybox therefore never rooted: the
caller's attest-key chain could not reach the Google root and verifiers
reported "unknown certificate".
Fall back to getAnyAttestationKey when no algorithm-matching keybox
exists. An EC attestation key validly ECDSA-signs an RSA-subject leaf,
so the EC keybox roots the RSA forge. No-op when the keybox is dual.