Revert "Allow overriding the label and icon of a MainComponent"

Revert submission 10403399-pkg-override-label-icon

Reason for revert: Droidcop: Potential culprit for Bug 152987173 - verifying through Forrest before revert submission. This is part of the standard investigation process, and does not mean your CL will be reverted.
Reverted Changes:
I4b20ec294:Add test constructor to PackageManagerService
Id48eda556:Allow overriding the label and icon of a MainCompo...

Change-Id: Ic5c719cbbd904f8cc1c5c6a6d826c7b807f03e39