compose: Do not use bootstrap css for "Enter to send" radio buttons.

We rewrite the CSS rules, handled by bootstrap for the radio buttons of
"Enter to send" setting, to compose.css as we are in process of
removing bootstrap.

The line-height property added to input element by bootstrap is not
added to subscriptions.css since it is already added for all inputs
in zulip.css.

static/styles/compose.css

@@ -486,6 +486,15 @@ input.recipient_box {
         input[type="radio"] {
             position: relative;
             top: 5px;
+            width: auto;
+            cursor: pointer;
+            margin: 4px 0 0;
+
+            &:focus {
+                outline: 1px dotted hsl(0, 0%, 20%);
+                outline: 5px auto -webkit-focus-ring-color;
+                outline-offset: -2px;
+            }
         }
 
         &:first-child {