lblistener: rename filter name certificate{,_id}

Previously we accept both, now with structured input we'd better choose
one and ignore the other.  Use certificate_id because that's the
console's choice

pkg/apis/compute/loadbalancer.go

@@ -48,7 +48,7 @@ type LoadbalancerListenerListInput struct {
 
 	Scheduler []string `json:"scheduler"`
 
-	Certificate []string `json:"certificate"`
+	Certificate []string `json:"certificate_id"`
 
 	SendProxy []string `json:"send_proxy"`
 

pkg/mcclient/options/loadbalancerlisteners.go

@@ -119,7 +119,7 @@ type LoadbalancerListenerListOptions struct {
 	XForwardedFor string `choices:"true|false"`
 	Gzip          string `choices:"true|false"`
 
-	Certificate     string
+	Certificate     string `json:"certificate_id"`
 	TLSCipherPolicy string
 	EnableHttp2     string `choices:"true|false"`