Strongbox may not support 1024 bit key size for RSA.

Strongbox may not support 1024 bit key size for RSA.
So in NoUserConfirmation test updated the key size to
2048 so that the test works for both TEE and Strongbox.

Bug: 280117495
Test: run VtsAidlKeyMintTarget
Change-Id: I32bb28001aca9b69eedb1bd3d0bcff43052d06e4