Remove ESLint verification when opting-out (#10499)

Author: mrmckeb

packages/react-scripts/scripts/utils/verifyPackageTree.js

@@ -13,6 +13,8 @@ const fs = require('fs');
 constsemver=require('semver');
 constpath=require('path');
 
+constisESLintPluginEnabled=process.env.DISABLE_ESLINT_PLUGIN!=='true';
+
 // We assume that having wrong versions of these
 // in the tree will likely break your setup.
 // This is a relatively low-effort way to find common issues.
@@ -21,14 +23,15 @@ function verifyPackageTree(){
 // These are packages most likely to break in practice.
 // See https://github.com/facebook/create-react-app/issues/1795 for reasons why.
 // I have not included Babel here because plugins typically don't import Babel (so it's not affected).
-'babel-eslint',
 'babel-jest',
 'babel-loader',
-'eslint',
 'jest',
 'webpack',
 'webpack-dev-server',
-];
+isESLintPluginEnabled&&'babel-eslint',
+isESLintPluginEnabled&&'eslint',
+].filter(Boolean);
+
 // Inlined from semver-regex, MIT license.
 // Don't want to make this a dependency after ejecting.
 constgetSemverRegex=()=>