e2e: fixup checkGatewayConfigAnnotation and clean up TestGatewayWithC…

…lassConfigChange (#199)

* e2e: refactor TestReferencePolicyLifecycle to use createGatewayClass

* e2e: refactor TestHTTPRouteFlattening to use createGatewayClass

* e2e: refactor TestHTTPMeshService to use createGatewayClass

* e2e: refactor TestTCPMeshService to use createGatewayClass

* e2e: remove extraneous GatewayClassConfig comments

* e2e: add GatewayClass status checks

* e2e: refactor CheckGatewayConfigAnnotation to get resource by name

clean up TestGatewayWithClassConfigChange

* e2e: pass resources to createGatewayClass and createGateway instead of cfg

* e2e: refactor to createGatewayClassWithParams helper

* e2e: set useHostPorts false for deployment replica tests

* e2e: replace 30*time.Second args with checkTimeout