Remove unnecessary method

Already implemented by the embedded struct.

Author: Andrew Farries

components/usage/pkg/apiv1/usage.go

@@ -5,9 +5,6 @@
 package apiv1
 
 import (
-	"context"
-	"fmt"
-
 	v1 "github.com/gitpod-io/gitpod/usage-api/v1"
 )
 
@@ -18,7 +15,3 @@ type UsageService struct {
 func NewUsageService() *UsageService {
 	return &UsageService{}
 }
-
-func (u *UsageService) GetUsage(context.Context, *v1.GetUsageRequest) (*v1.GetUsageResponse, error) {
-	return nil, fmt.Errorf("RPC not implemented")
-}