api-gateway: stop adding all header filters to virtual host when generating xDS (#17644)

* Add header filter to api-gateway xDS golden test

* Stop adding all header filters to virtual host when generating xDS for api-gateway

* Regenerate xDS golden file for api-gateway w/ header filter

agent/xds/resources_test.go

@@ -415,6 +415,19 @@ func getAPIGatewayGoldenTestCases(t *testing.T) []goldenTestCase {
 						Kind: structs.HTTPRoute,
 						Name: "route",
 						Rules: []structs.HTTPRouteRule{{
+							Filters: structs.HTTPFilters{
+								Headers: []structs.HTTPHeaderFilter{
+									{
+										Add: map[string]string{
+											"X-Header-Add": "added",
+										},
+										Set: map[string]string{
+											"X-Header-Set": "set",
+										},
+										Remove: []string{"X-Header-Remove"},
+									},
+								},
+							},
 							Services: []structs.HTTPService{{
 								Name: "service",
 							}},

agent/xds/routes.go

@@ -477,8 +477,6 @@ func (s *ResourceGenerator) routesForAPIGateway(cfgSnap *proxycfg.ConfigSnapshot
 				return nil, err
 			}
 
-			addHeaderFiltersToVirtualHost(&reformatedRoute, virtualHost)
-
 			defaultRoute.VirtualHosts = append(defaultRoute.VirtualHosts, virtualHost)
 		}
 
@@ -1097,16 +1095,6 @@ func injectHeaderManipToRoute(dest *structs.ServiceRouteDestination, r *envoy_ro
 	return nil
 }
 
-func addHeaderFiltersToVirtualHost(dest *structs.HTTPRouteConfigEntry, vh *envoy_route_v3.VirtualHost) {
-	for _, rule := range dest.Rules {
-		for _, header := range rule.Filters.Headers {
-			vh.RequestHeadersToAdd = append(vh.RequestHeadersToAdd, makeHeadersValueOptions(header.Add, true)...)
-			vh.RequestHeadersToAdd = append(vh.RequestHeadersToAdd, makeHeadersValueOptions(header.Set, false)...)
-			vh.RequestHeadersToRemove = append(vh.RequestHeadersToRemove, header.Remove...)
-		}
-	}
-}
-
 func injectHeaderManipToVirtualHost(dest *structs.IngressService, vh *envoy_route_v3.VirtualHost) error {
 	if !dest.RequestHeaders.IsZero() {
 		vh.RequestHeadersToAdd = append(

agent/xds/testdata/routes/api-gateway-with-http-route-and-inline-certificate.latest.golden

@@ -18,7 +18,26 @@
               },
               "route": {
                 "cluster": "service.default.dc1.internal.11111111-2222-3333-4444-555555555555.consul"
+              },
+              "requestHeadersToAdd": [
+                {
+                  "header": {
+                    "key": "X-Header-Add",
+                    "value": "added"
+                  },
+                  "append": true
+                },
+                {
+                  "header": {
+                    "key": "X-Header-Set",
+                    "value": "set"
+                  },
+                  "append": false
                 }
+              ],
+              "requestHeadersToRemove": [
+                "X-Header-Remove"
+              ]
             }
           ]
         }