Get rid of DeviceName() from path related to dexpreopt

As-is, dexpreopt config and bootjar is in the dir including
DeviceName(). It causes unnecessary dexpreopt invocation when target is
changed repeatly. To avoid it, rename dir to common name.

Bug: 278833696
Test: m
Change-Id: I2818d9ae09e6c22ca6989cc8efdb70b470ec502c