Revert "Merge pull request #1865 from basecamp/public-avatar-caching"

This reverts commit c628f14c01, reversing
changes made to 4bafc73236.

test/controllers/users/avatars_controller_test.rb

@@ -12,10 +12,17 @@ class Users::AvatarsControllerTest < ActionDispatch::IntegrationTest
     assert_redirected_to ActionController::Base.helpers.image_path("system_user.png")
   end
 
-  test "show initials with public caching" do
+  test "show own initials without caching" do
     get user_avatar_path(users(:david))
     assert_match "image/svg+xml", @response.content_type
-    assert @response.cache_control[:public]
+    assert @response.cache_control[:private]
+    assert_equal "0", @response.cache_control[:max_age]
+  end
+
+  test "show other initials with caching" do
+    get user_avatar_path(users(:kevin))
+    assert_match "image/svg+xml", @response.content_type
+    assert @response.cache_control[:private]
     assert_equal 30.minutes.to_s, @response.cache_control[:max_age]
   end