settings_bots: Remove redundant code.
settings_bots: Remove redundant code.

This commit removes the redundant code to update the
"src" attribute of bot avatar on changing avatar added
in f7ca0117e68d.

We do not need to add version to the url since the backend
already sends url with latest version number and also we
already re-render the bots page after recieving realm_bot/update
event.

andersk/zulip,rht/zulip,rht/zulip,zulip/zulip,zulip/zulip,zulip/zulip,zulip/zulip,andersk/zulip,andersk/zulip,andersk/zulip,zulip/zulip,andersk/zulip,andersk/zulip,rht/zulip,andersk/zulip,rht/zulip,rht/zulip,zulip/zulip,zulip/zulip,rht/zulip,rht/zulip