Change clear notifications to have more readable copy (#9867)

Author: Germain

src/components/views/settings/Notifications.tsx

@@ -642,7 +642,7 @@ export default class Notifications extends React.PureComponent<IProps, IState> {
                     className="mx_UserNotifSettings_clearNotifsButton"
                     data-testid="clear-notifications"
                 >
-                    {_t("Clear notifications")}
+                    {_t("Mark all as read")}
                 </AccessibleButton>
             );
         }

src/i18n/strings/en_EN.json

@@ -1419,7 +1419,7 @@
     "Enable desktop notifications for this session": "Enable desktop notifications for this session",
     "Show message in desktop notification": "Show message in desktop notification",
     "Enable audible notifications for this session": "Enable audible notifications for this session",
-    "Clear notifications": "Clear notifications",
+    "Mark all as read": "Mark all as read",
     "Keyword": "Keyword",
     "New keyword": "New keyword",
     "On": "On",
@@ -2126,7 +2126,6 @@
     "%(count)s reply|one": "%(count)s reply",
     "Open thread": "Open thread",
     "Jump to first unread message.": "Jump to first unread message.",
-    "Mark all as read": "Mark all as read",
     "Unable to access your microphone": "Unable to access your microphone",
     "We were unable to access your microphone. Please check your browser settings and try again.": "We were unable to access your microphone. Please check your browser settings and try again.",
     "No microphone found": "No microphone found",