Merge and use IS_PRODUCTION context processor everywhere

src/registrar/templates/home.html

@@ -13,7 +13,7 @@
   <h1>Manage your domains</h2>
 
   <p class="margin-top-4">
-    {% if is_production %}
+    {% if IS_PRODUCTION %}
     <a href="javascript:void(0)" 
     class="usa-button usa-tooltip disabled-link"
     data-position="right"

src/registrar/views/index.py

@@ -2,7 +2,6 @@ from django.db.models import F
 from django.shortcuts import render
 
 from registrar.models import DomainApplication
-from django.conf import settings
 
 
 def index(request):
@@ -23,5 +22,4 @@ def index(request):
             state=F("domain__state"),
         )
         context["domains"] = domains
-        context["is_production"] = settings.IS_PRODUCTION
     return render(request, "home.html", context)