fix: remove HOME_PATH (#43034)

It was only used as a default for hardGoTo, but that function is only
called once and does not need the default

client/gatsby-node.js

@@ -167,13 +167,8 @@ exports.createPages = function createPages({ graphql, actions, reporter }) {
 
 const MonacoWebpackPlugin = require('monaco-editor-webpack-plugin');
 
-exports.onCreateWebpackConfig = ({ stage, plugins, actions }) => {
+exports.onCreateWebpackConfig = ({ stage, actions }) => {
   const newPlugins = [
-    plugins.define({
-      HOME_PATH: JSON.stringify(
-        process.env.HOME_PATH || 'http://localhost:3000'
-      )
-    }),
     // We add the shims of the node globals to the global scope
     new webpack.ProvidePlugin({
       Buffer: ['buffer', 'Buffer']

client/src/redux/hard-go-to-epic.js

@@ -1,4 +1,3 @@
-/* global HOME_PATH */
 import { ofType } from 'redux-observable';
 import { tap, ignoreElements } from 'rxjs/operators';
 
@@ -7,7 +6,7 @@ import { types } from './';
 export default function hardGoToEpic(action$, _, { location }) {
   return action$.pipe(
     ofType(types.hardGoTo),
-    tap(({ payload = HOME_PATH }) => {
+    tap(({ payload }) => {
       location.href = payload;
     }),
     ignoreElements()