gha: Use server side apply in Gateway API

This commit is to use `kubectl apply` in the Gateway API conformance
tests to be server-side. This is required for the v1.4.0 HTTPRoute CRD
object to  apply, as client-side apply creates a `last-applied-config`
annotation that is now greater than the maximum size of 256kb.

Sample error
```
The CustomResourceDefinition "httproutes.gateway.networking.k8s.io" is invalid: metadata.annotations: Too long: may not be more than 262144 bytes
```

Signed-off-by: Tam Mach <[email protected]>

Author: sayboras

.github/workflows/cilium-gateway-api.yaml

@@ -83,13 +83,13 @@ jobs:
         run: |
           gateway_api_version=$(grep -m 1 "sigs.k8s.io/gateway-api" go.mod | awk '{print $2}' | awk -F'-' '{print (NF>2)?$NF:$0}')
           # Install Gateway CRDs
-          kubectl apply -f https://raw.githubusercontent.com/kubernetes-sigs/gateway-api/$gateway_api_version/config/crd/experimental/gateway.networking.k8s.io_gatewayclasses.yaml
-          kubectl apply -f https://raw.githubusercontent.com/kubernetes-sigs/gateway-api/$gateway_api_version/config/crd/experimental/gateway.networking.k8s.io_gateways.yaml
-          kubectl apply -f https://raw.githubusercontent.com/kubernetes-sigs/gateway-api/$gateway_api_version/config/crd/experimental/gateway.networking.k8s.io_httproutes.yaml
-          kubectl apply -f https://raw.githubusercontent.com/kubernetes-sigs/gateway-api/$gateway_api_version/config/crd/experimental/gateway.networking.k8s.io_referencegrants.yaml
-          kubectl apply -f https://raw.githubusercontent.com/kubernetes-sigs/gateway-api/$gateway_api_version/config/crd/experimental/gateway.networking.k8s.io_grpcroutes.yaml
+          kubectl apply --server-side -f https://raw.githubusercontent.com/kubernetes-sigs/gateway-api/$gateway_api_version/config/crd/experimental/gateway.networking.k8s.io_gatewayclasses.yaml
+          kubectl apply --server-side -f https://raw.githubusercontent.com/kubernetes-sigs/gateway-api/$gateway_api_version/config/crd/experimental/gateway.networking.k8s.io_gateways.yaml
+          kubectl apply --server-side -f https://raw.githubusercontent.com/kubernetes-sigs/gateway-api/$gateway_api_version/config/crd/experimental/gateway.networking.k8s.io_httproutes.yaml
+          kubectl apply --server-side -f https://raw.githubusercontent.com/kubernetes-sigs/gateway-api/$gateway_api_version/config/crd/experimental/gateway.networking.k8s.io_referencegrants.yaml
+          kubectl apply --server-side -f https://raw.githubusercontent.com/kubernetes-sigs/gateway-api/$gateway_api_version/config/crd/experimental/gateway.networking.k8s.io_grpcroutes.yaml
           ## TLSRoute is only available in experimental channel in v0.7.0
-          kubectl apply -f https://raw.githubusercontent.com/kubernetes-sigs/gateway-api/$gateway_api_version/config/crd/experimental/gateway.networking.k8s.io_tlsroutes.yaml
+          kubectl apply --server-side -f https://raw.githubusercontent.com/kubernetes-sigs/gateway-api/$gateway_api_version/config/crd/experimental/gateway.networking.k8s.io_tlsroutes.yaml
 
           # To make sure that Gateway API CRs are available
           kubectl wait --for condition=Established crd/gatewayclasses.gateway.networking.k8s.io --timeout=${{ env.timeout }}