Rename system property to enable KeyMint VM

This allows us to regroup Widevine VM under the same trusty
group.

Bug: 368502791
Test: launch_cvd --secure_hals=guest_keymint_trusty_insecure
Test: atest VtsAidlSharedSecretTargetTest
Change-Id: Ica76a896e99f70a64af229bda68622a2ce0dea1f
1 file changed