Revert "Add benchmark for building docs site"

We already have a lot of site building benchmarks. The main problem with adding the "Hugo site docs" to the list is that it cannot easiliy  be compared to any previous release, because its content/template/whatever has changed.

This reverts commit 837e084bbe.

main_test.go

@@ -1,35 +0,0 @@
-// Copyright 2020 The Hugo Authors. All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package main
-
-import (
-	"testing"
-
-	"github.com/gohugoio/hugo/commands"
-)
-
-func BenchmarkDocsSite(b *testing.B) {
-	flags := []string{
-		"--quiet",
-		"--source=docs",
-		"--renderToMemory",
-	}
-
-	for i := 0; i < b.N; i++ {
-		r := commands.Execute(flags)
-		if r.Err != nil {
-			b.Fatal(r.Err)
-		}
-	}
-}