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