Restrict netd fwk policy.

Remove netd access to sysfs_type attribute.

These were moved from vendor to fwk policy:
1. sysfs_net type declaration
2. labeling of /sys/devices/virtual/net with sysfs_net
3. netd access to sysfs_net

Bug: 65643247
Test: can browse internet without netd denials
Test: netd_unit_test, netd_integration_test without netd denials
Merged-In: Ic1b95a098f438c4c6bc969bee801bf7dd1a13f6e
Change-Id: Ic1b95a098f438c4c6bc969bee801bf7dd1a13f6e
(cherry picked from commit e62a56b7)