[pm] Add null check and return first

If the package doesn't exist, don't need to proceed to
setPackageStoppedState in notifyComponentUsed. Return it first.

Bug: 299565095
Test: atest DevicePolicyManagerServiceMigrationTest
Test: atest SuspendPackageHelperTest
Test: atest PackageManagerSettingsTests
Test: atest AppCloningMediaProviderHostTest --iterations 100
Change-Id: I7aff7887e54d023d25ea62d2aad928e45d0fc448