Initial clean-up of NatService integration test

Make the structure/setup more like FirewallService tests
Test we have got the expected number of NAT rules
Fix bug with SNAT rule specifying protocol

* discovered with diff test, added in this commit
NatService Idempotency test enabled

... and passing, now protocol bug is fixed
add basic DNAT/SNAT rule default tests

* DRY out tests accordingly
Add tests confirming defaults for SNAT/DNAT

Ensure we test the 'full rule' case for defaults, to ensure that
we are testing that additional fields (such as 'Protocol' in the SNAT case'
are not appearing unexpectedly.
Add SNAT specific "disabled rule" test

and rename DNAT test for clarity
Add UDP DNAT test
Fix uncovered DNAT protocol bug

UDP test highlighted that we were not handling "protocol" correctly
Merge branch 'master' into nat-test-fixes
Improve "only run once" test

* remove rspec matcher to avoid rspec altering our code path

* instead number of networkConfigureEdgeGatewayServices tasks via Query API
Speed up retrieval of EdgeGateway update tasks

This commit enables retrieving tasks from a specific DateTime
timestamp, which should speed up the check for 'how many updates
have happened since we started'
Merge pull request #142 from alphagov/nat-test-fixes

[#64582784] Fix SNAT bug causing issues with diff/idempotency