Do not try to activate apexes without .pb manifest

When there are some problematic apexes which have only
apex_manifest.json in its container, but both .pb and .json manifests in
the image (filesystem), apexd fails to activate them.

Filtering out them so that it won't cause any problems during OTA or
something.

Bug: 149388490
Test: atest --test-mapping system/apex/apexd
      atest apexd_host_test
      adb push problematic-apex /data/apex/active
      adb reboot # successfully boot

Change-Id: I2b7313575ed468d2a82142dd6b2a67a89cbdfe7a
6 files changed