Edge firewall might contain FW rules which are originated from various
sources, e.g FWaaS rules, subnet rules, LB rules etc.
When a non-admin user applies a change to the FW config by changing any
of the above, the new FW config should still include resources which
aren't visible to the user. Therefore the context should be elevated.
Change-Id: I8cd3310976708b0bbf1442de7f38ebc06dc8506a