Delete render file tests

These tests are now failing because of changes made in
rails/rails#35688. This causes the instrumentation for `@_files` to not
get run, but also don't think this should be supported since that
instrumentation is for templates and now files are just rendered as
files not as templates.

test/controllers/template_assertions_test.rb

@@ -12,11 +12,6 @@ def test_with_partial
     assert_template partial: '_partial'
   end
 
-  def test_file_with_absolute_path_success
-    get :render_file_absolute_path
-    assert_template file: File.expand_path('../../dummy/README.rdoc', __FILE__)
-  end
-
   def test_file_with_relative_path_success
     get :render_file_relative_path
     assert_template file: 'README.rdoc'
@@ -28,12 +23,6 @@ def test_with_file_failure
     assert_raise(ActiveSupport::TestCase::Assertion) do
       assert_template :file => 'test/hello_world'
     end
-
-    get :render_file_absolute_path
-
-    assert_raise(ActiveSupport::TestCase::Assertion) do
-      assert_template file: nil
-    end
   end
 
   def test_with_nil_passes_when_no_template_rendered