Respect package source from adb install

The package source is set to PACKAGE_SOURCE_OTHER in PackageManager-
ShellCommand by default. However, the source would be overrided to
PACKAGE_SOURCE_UNSPECIFIED if installerPackageName is null in the
InstallSource#createInternal. We should respect the package source
if it's set.

Bug: 240114543
Test: atest CtsPackageInstallTestCases:InstallSourceInfoTest
Test: manually install an app via adb install, and check the source
Change-Id: Ide5851d17d82bb3f20693b62348e303226f97a48