Install dexpreopt artifacts of SpeedApps in system_other

The dexpropt'd files for Speed apps are currently installed next to the
.apk file. This CL modifies the installation path of these dexpreopt
artifacts to /system_other.

Bug: 349083274
Test: for cf_x86_64_phone-trunk_staging-userdebug, verified that
SystemUIGoogle.odex appears in installed-files-system-other.txt and
_not_ installed-files-system-ext.txt

Test: In device boot logs, found the following match
Successfully loaded /data/dalvik-cache/arm64/system_ext@priv-app@SystemUIGoogle@SystemUIGoogle.apk@classes.dex with executable: 0

Change-Id: I5dd6ea7c1291a568ffdc2f4f23aaee4f806b1998