ApexManager does nothing when ro.apex.updatable is false

When ro.apex.updatable isn't set, apexd service does not run. Therefore
ApexManager should not try to talk to the native service in that case.

Bug: 132413565
Bug: 131697251
Bug: 133856241
Test: marlin, aosp_bonito are bootable
Merged-In: I4285df01a75d57e89e03f98aafde3860de86e9a0
Change-Id: I4285df01a75d57e89e03f98aafde3860de86e9a0
(cherry picked from commit c53878f3)