AOSP KeyMint only includes the attestation extension (OID
1.3.6.1.4.1.11129.2.1.17) when ATTESTATION_CHALLENGE is present.
Without a challenge, generateKey produces a plain self-signed cert.
Our code unconditionally added the extension, which behavioral
probes detect by generating a key without a challenge and checking
for the OID.
Fixes both the Rust native-certgen and BouncyCastle paths.
Also skips AAID computation when no challenge is provided,
matching keystore2 security_level.rs:457 behavior.