Another fix for a memory leak. This one is not as big as #4150, but
still worth fixing for memory constrained devices imo.
The `DrawerImageLoader` implementation (a global singleton) references a
member of the `MainActivity`, causing the whole activity to leak.
This weird construct was introduced in #1989 to fix a crash, but I think
since we migrated to coroutines it is no longer necessary because all
calls get correctly cancelled. I tried reproducing the crash but could
not, so I'm pretty sure it is fine. I would appreciate it if someone
else could try it as well though.
(The crash could be reproduced on slow internet, when
`onFetchUserInfoSuccess` was called while the activity was being
destroyed, causing Glide to crash the app because it can't use destroyed
activities. `onFetchUserInfoSuccess` is now no longer called in this
case because it is inside a `lifecycleScope.launch` block.)
75c42cb5c1