Don't use confirm dialog in admin homepage form

In this case the confirmation dialog isn't really necessary since the
action to enable/disable the setting can easily be undone.

Furthermore, these tests were failing with Chrome 83, probably because
we use `confirm_dialog` and then we use `visit` without checking the
page in between.

In theory we shouldn't need to check the page in between because the
request generated by `confirm_dialog` is a synchronous one and so
`visit` isn't executed after the previous request has finished, but
apparently this behavior has changed in Chrome 83.

We could add an expectation before executing the `visit` method, but
that wouldn't improve the usability of the application.

spec/system/admin/homepage/homepage_spec.rb

@@ -36,7 +36,7 @@ describe "Homepage" do
 
       within("#widget_feed_#{proposals_feed.id}") do
         select "1", from: "widget_feed_limit"
-        accept_confirm { click_button "Enable" }
+        click_button "Enable"
       end
 
       visit root_path
@@ -55,7 +55,7 @@ describe "Homepage" do
       visit admin_homepage_path
       within("#widget_feed_#{debates_feed.id}") do
         select "2", from: "widget_feed_limit"
-        accept_confirm { click_button "Enable" }
+        click_button "Enable"
       end
 
       visit root_path
@@ -76,12 +76,12 @@ describe "Homepage" do
 
       within("#widget_feed_#{proposals_feed.id}") do
         select "3", from: "widget_feed_limit"
-        accept_confirm { click_button "Enable" }
+        click_button "Enable"
       end
 
       within("#widget_feed_#{debates_feed.id}") do
         select "3", from: "widget_feed_limit"
-        accept_confirm { click_button "Enable" }
+        click_button "Enable"
       end
 
       visit root_path
@@ -106,7 +106,7 @@ describe "Homepage" do
       visit admin_homepage_path
       within("#widget_feed_#{processes_feed.id}") do
         select "3", from: "widget_feed_limit"
-        accept_confirm { click_button "Enable" }
+        click_button "Enable"
       end
 
       visit root_path