KeyMint: use a smaller invalid IMEI value

The invalid value used for the second IMEI attestation test is
potentially wrong in two ways:
- It doesn't match the provisioned value.
- It's not a valid IMEI, not least because it is longer than 16 bytes.

Make the test value shorter so the second failure doesn't apply and
the test can reliably expect CANNOT_ATTEST_IDS.

Bug: 292959871
Test: VtsAidlKeyMintTargetTest
Change-Id: If8c6b9e08b48e6caf5c767578e1ac43964214619

security/keymint/aidl/vts/functional/AttestKeyTest.cpp

@@ -919,7 +919,9 @@ TEST_P(AttestKeyTest, EcdsaAttestationMismatchID) {
                     .Authorization(TAG_ATTESTATION_ID_MODEL, "malicious-model");
 
     if (isSecondImeiIdAttestationRequired()) {
-        attestation_id_tags.Authorization(TAG_ATTESTATION_ID_SECOND_IMEI, "invalid-second-imei");
+        // Note: the invalid value here is < 16 bytes long to avoid triggering any implementation
+        // checks on valid IMEI lengths.
+        attestation_id_tags.Authorization(TAG_ATTESTATION_ID_SECOND_IMEI, "invalid-imei2");
     }
     vector<uint8_t> key_blob;
     vector<KeyCharacteristics> key_characteristics;