[pm] prevent system app downgrades of versions lower than preload

Also remove misleading commandline output.

BUG: 256202273

Test: manual
1. Install preload system app v90, reboot
2. (W/O data, W/ Flag, 90->80 NOK) adb install -d ~/Downloads/PrivApplication_80.apk
Performing Streamed Install
adb: failed to install /usr/local/google/home/schfan/Downloads/PrivApplication_80.apk: Failure [INSTALL_FAILED_VERSION_DOWNGRADE: System app: com.example.privapplication cannot be downgraded to older than its preloaded version on the system image. Update version code 80 is older than current 90]
3. (90->100) Install data app v100
4. (W/ data, W/O Flag, 100->90 NOK) adb install ~/Downloads/PrivApplication_90.apk
Performing Streamed Install
adb: failed to install /usr/local/google/home/schfan/Downloads/PrivApplication_90.apk: Failure [INSTALL_FAILED_VERSION_DOWNGRADE: Downgrade detected: Update version code 90 is older than current 100]
5. (W/ data, W/ Flag, 100->90 downgrade OK) adb install -d ~/Downloads/PrivApplication_90.apk
Performing Streamed Install
Success
6. (90->100) Install v100
6. (W/data, W/ Flag, 100->80 NOK) adb install -d ~/Downloads/PrivApplication_80.apk
Performing Streamed Install
adb: failed to install /usr/local/google/home/schfan/Downloads/PrivApplication_80.apk: Failure [INSTALL_FAILED_VERSION_DOWNGRADE: System app: com.example.privapplication cannot be downgraded to older than its preloaded version on the system image. Update version code 80 is older than current 90]

Change-Id: I5a8ee9e29a3a58f6e3fd188e0122355744b8b0ce