browsers: remove IE-specific browser detection

- It doesn't work in IE >=10 (as support for conditionnal comments was
  removed)
- It is redundant with our all-browsers detection anyway

app/views/layouts/_ie_lt_10.html.haml

@@ -1,8 +0,0 @@
-<!--[if lt IE 10]>
-
-.center{ style: 'width: 100%; background-color: white; position: fixed; top: 0; left: 0; z-index: 100000;' }
-  %h3.text-danger
-    %b
-      Votre version d'Internet Explorer est trop ancienne pour être utilisée sur demarches-simplifiees.fr. Version minimum : Internet Explorer 10
-
-<![endif]-->

app/views/layouts/application.html.haml

@@ -25,8 +25,6 @@
       #beta
         Env Test
 
-    = render partial: 'layouts/ie_lt_10'
-
     #wrap
       .row
         #header.navbar

app/views/layouts/new_application.html.haml

@@ -26,7 +26,6 @@
   %body
     .page-wrapper
       = render partial: "layouts/support_navigator_banner"
-      = render partial: "layouts/ie_lt_10"
       = render partial: 'layouts/pre_maintenance'
       - if Rails.env == "staging"
         #beta