Fix getKeySetByAlias PackageMgr test.

commit 42aed1b8ecf591009f9e2df8eaca4f41074c37c8 changed the hidden
KeySet API to allow packages to retrieve keysets of other packages.
Change the PackageManagerTests to not expect a SecurityExeption
anymore and also make sure that this is supported.

Bug: 25935839
Change-Id: I18c00997a627c9df1eb3826650c1aa71f563a2bd
2 files changed