UI in settings for bot owners to unsubscribe their bots from streams, Personal settings > Bots > Bot info card > hashtag icon. Fixes: #22460
The feature deactivates the bot user; Zulip has no "delete bot" feature. So fix the label to match what it does. We also change the icon to match the one we use for deactivating users in the "Manage users" UI.
Since templates for settings UI should be in `static/templates/settings`.