Update conformance test to assert observedGeneration is bumped

[dprotaso]

As a follow up to #1364 we should update conformance tests to assert that each condition's observeredGeneration is incremented to match the resource's metadata.generation

This is important because as updates occur to a resource's spec block (which increments metadata.generation) it implies the conditions are stale until the controller acknowledges them.

Also the language in the GEP is a bit confusing

observedGeneration is an optional field that sets what the metadata.generation field was when the controller last saw a resource. Note that this is optional in the struct, but is required for Gateway API conditions. This will be enforced in the conformance tests in the future.

I would probably just state that observedGeneration is required to be set by gateway implementations and ignore mentioning that there's an +optional marker

[youngnick]

Yeah, reading it back, that is confusing, thanks. I'll do a small PR to update that. But agreed that we should check observedGeneration matches correctly as well.

[dprotaso]

/assign @dprotaso