Remove the OverlayInfos without impacts target set

Most of packages are not related to overlay. It means that
* the package is not overlaid by others
* the package doesn't overlay any package.
The rate of packages overlaid by other packages is 31/231.

This patch not only removes the unnecessary OverlayInfo in memory
but also speeds the performance up.

Bug: 174206591

Test: atest \
            OverlayHostTests \
            OverlayDeviceTests \
            OverlayRemountedTest \
            FrameworksServicesTests:com.android.server.om \
            CtsContentTestCases:android.content.om.cts \
            idmap2_tests
Change-Id: Iafd88b89d0d0a51f737e10aa86ec0b348cd9d431