tests: add helm upgrade tests

[pmalek]

What this PR does / why we need it:

This PR adds some basic scaffolding for helm upgrade tests

Which issue this PR fixes

Part of #155

Special notes for your reviewer:

In order to perform update form pre 1.2 to 1.2+ we need to be able to disable ControlPlane and Gateway controllers because their respective CRDs (ControlPlane and GatewayConfiguration) got a breaking change in 1.2 (bump from v1alpha1 to v1beta without a KGO version that would allow a smooth transition).

This requires a change in the chart which would allow setting args because only KGO 1.2+ supports configuration via env. Kong/charts#1058 implements that.

The upgrade from pre 1.2 to 1.2 and up is not done as helm chart (used in this test suite) only contains the CRDs from 1.2 and since helm still doesn't provide CRD management there's no easy way to achieve that (well apart from applying the CRDs manually but we'd need to add manual steps for that).

PR Readiness Checklist:

Complete these before marking the PR as ready to review:

• the CHANGELOG.md release notes have been updated to reflect significant changes

[programmer04]

Have you tested it with KGO EE? It seems it should work, but it's better to be sure 😉

[pmalek]

Have you tested it with KGO EE? It seems it should work, but it's better to be sure 😉

Good point. I've created https://github.com/Kong/gateway-operator-enterprise/pull/137 to test this

[pmalek]

Have you tested it with KGO EE? It seems it should work, but it's better to be sure 😉

Good point. I've created Kong/gateway-operator-enterprise#137 to test this

@programmer04 https://github.com/Kong/gateway-operator-enterprise/pull/137#issuecomment-2096470896