Inhibit loading messages when fragment is paused.
Inhibit loading messages when fragment is paused.

We were getting a spurious scroll event at 0 just before the onResume when
un-narrowing, which caused it to load another batch of messages above.

prati0100/zulip-android,prati0100/zulip-android,abhaymaniyar/zulip-android,Sam1301/zulip-android,saketkumar95/zulip-android,zulip/zulip-android,saketkumar95/zulip-android,Sam1301/zulip-android,vishwesh3/zulip-android,abhaymaniyar/zulip-android