Remove mock-plugin binary causing circular dep

sdk/plugin/mock/mock-plugin/main.go

@@ -1,31 +0,0 @@
-package main
-
-import (
-	"log"
-	"os"
-
-	"github.com/hashicorp/vault/api"
-	"github.com/hashicorp/vault/sdk/logical"
-	"github.com/hashicorp/vault/sdk/plugin"
-	"github.com/hashicorp/vault/sdk/plugin/mock"
-)
-
-func main() {
-	apiClientMeta := &api.APIClientMeta{}
-	flags := apiClientMeta.FlagSet()
-	flags.Parse(os.Args[1:]) // Ignore command, strictly parse flags
-
-	tlsConfig := apiClientMeta.GetTLSConfig()
-	tlsProviderFunc := api.VaultPluginTLSProvider(tlsConfig)
-
-	factoryFunc := mock.FactoryType(logical.TypeLogical)
-
-	err := plugin.Serve(&plugin.ServeOpts{
-		BackendFactoryFunc: factoryFunc,
-		TLSProviderFunc:    tlsProviderFunc,
-	})
-	if err != nil {
-		log.Println(err)
-		os.Exit(1)
-	}
-}