(Temporarily?) delay path changes and global cache changes

There are several issues with these which I'm not sure I'll have time to
address properly. I prefer to keep our default branch in a releasable
state just in case. Once they are fixed, this can be reverted.

lib/bundler/cli/common.rb

@@ -130,7 +130,7 @@ module Bundler
     def self.clean_after_install?
       clean = Bundler.settings[:clean]
       return clean unless clean.nil?
-      clean ||= Bundler.feature_flag.bundler_4_mode? && Bundler.settings[:path].nil?
+      clean ||= Bundler.feature_flag.bundler_5_mode? && Bundler.settings[:path].nil?
       clean &&= !Bundler.use_system_gems?
       clean
     end

lib/bundler/feature_flag.rb

@@ -30,7 +30,7 @@ module Bundler
     settings_flag(:allow_offline_install) { bundler_4_mode? }
     settings_flag(:cache_all) { bundler_4_mode? }
     settings_flag(:forget_cli_options) { bundler_4_mode? }
-    settings_flag(:global_gem_cache) { bundler_4_mode? }
+    settings_flag(:global_gem_cache) { bundler_5_mode? }
     settings_flag(:lockfile_checksums) { bundler_4_mode? }
     settings_flag(:plugins) { @bundler_version >= Gem::Version.new("1.14") }
     settings_flag(:update_requires_all_flag) { bundler_5_mode? }

lib/bundler/settings.rb

@@ -272,7 +272,7 @@ module Bundler
       def use_system_gems?
         return true if system_path
         return false if explicit_path
-        !Bundler.feature_flag.bundler_4_mode?
+        !Bundler.feature_flag.bundler_5_mode?
       end
 
       def base_path

spec/bundler/commands/clean_spec.rb

@@ -427,7 +427,7 @@ RSpec.describe "bundle clean" do
     should_not_have_gems "foo-1.0"
   end
 
-  it "automatically cleans when path has not been set", bundler: "4" do
+  it "automatically cleans when path has not been set", bundler: "5" do
     build_repo2
 
     install_gemfile <<-G

spec/bundler/commands/install_spec.rb

@@ -38,6 +38,15 @@ RSpec.describe "bundle install with gem sources" do
       expect(bundled_app(".bundle")).not_to exist
     end
 
+    it "will create a ./.bundle by default", bundler: "5" do
+      install_gemfile <<-G
+        source "https://gem.repo1"
+        gem "myrack"
+      G
+
+      expect(bundled_app(".bundle")).to exist
+    end
+
     it "does not create ./.bundle by default when installing to system gems" do
       install_gemfile <<-G, env: { "BUNDLE_PATH__SYSTEM" => "true" }
         source "https://gem.repo1"

spec/bundler/support/filters.rb

@@ -32,7 +32,7 @@ RSpec.configure do |config|
 
   config.filter_run_when_matching :focus unless ENV["CI"]
 
-  config.before(:each, bundler: "4") do
-    bundle "config simulate_version 4"
+  config.before(:each, :bundler) do |example|
+    bundle "config simulate_version #{example.metadata[:bundler]}"
   end
 end