Clean up the permission control code in framework

Delete the unused NetworkManagementService API for set/remove
permissions. Use PERMISSION_NONE to replace NO_PERMISSIONS so the
framework now use the same set of permission constant when communicate
with netd.

Bug: 128944261
Test: PermissionMonitorTest.java

Change-Id: I25224c9576f52d2a0a0bd2182325c7aac7b28eb5