fix: fix applicant messager drawer refusing to close in some cases (#…

…3110) (HL-1345)

Closing the sidebar changed the isMessagesDrawerVisible value, which
was a dependency for the same useEffect that was responsible for
opening it upon the query parameter in the first place. Now that
function is isolated into its own useEffect and doesn't get rerun.

frontend/benefit/applicant/src/components/header/useHeader.ts

@@ -67,10 +67,13 @@ const useHeader = (): ExtendedComponentProps => {
     if (isMessagesDrawerVisible && Number(unreadMessagesCount) > 0) {
       setUnredMessagesCount(null);
     }
+  }, [isMessagesDrawerVisible, unreadMessagesCount]);
+
+  useEffect(() => {
     if (openDrawer) {
       setMessagesDrawerVisiblity(true);
     }
-  }, [isMessagesDrawerVisible, unreadMessagesCount, openDrawer]);
+  }, [openDrawer]);
 
   const status = React.useMemo(
     (): APPLICATION_STATUSES =>