Make gateway fixture session scope

[pehala]

• Solves problems with limitador test concurrency failures
• Increases time for running individual tests but doesn't change overall test time even if load balancers take a while
• Individual tests still can use module scope GW
  • MGC still uses it

Thanks @azgabur for investigating!

PS: copy of #362, which I inexplicably closed

Fixes #324

[azgabur]

I just noticed the make authorino-standalone is erorring out with ScopeMismatch. Not approved yet.

[pehala]

I just noticed the make authorino-standalone is erorring out with ScopeMismatch. Not approved yet.

Thanks to you and also @averevki (who also reported the same issue). It should be fixed now

[azgabur]

This PR will solve limitador tests concurrency issues. But will also create some new ones:

• In case the Gateway object will never reconcile due to some error, testsuite will show error only after gw.wait_for_ready() timeout, which is currently 10 minutes
• The current timeout is enough for our Openstack testing environment, but just barely.
  • Raising number of threads from default 4 to more will cause timeout errors.
  • Running the testsuite in parallel, which can happen if two people run it on the same environment at the same time, will cause timeout errors at least in one of those runs.
  • Running testsuite just after finishing previous run will cause timeout errors because of slowly deleting load balancers.
• Quickly debugging functionality of single test will now take ~2 minutes on our testing environment even if most of the authorino tests do not need the gateway to reconcile to function properly.

Overall I recommend making the timeout a variable in settings.yaml so it can be adjusted before running testsuite if the testing environment is faster/slower. This can be done in next PR.

I also recommend to watch the changes in workflow of test development, namely longer waits in running tests and see later if it needs to be adjusted or no. Adjustments could be for example making the session scope as an development option in settings.yaml or making the limitador tests the only ones who require the session scope.