msglist [nfc]: Remove one `Center` widget (because no-op); comment to explain another#1042

gnprice merged 3 commits intozulip:mainzulip/zulip-flutter:mainfrom

chrisbobbe:pr-msglist-center-widgets-nfcchrisbobbe/zulip-flutter:pr-msglist-center-widgets-nfcCopy head branch name to clipboard