[Msa] Don't trigger Render overview when switching to another window

The "Render overview" task starts when switching from an AE window to any window. It doesn't make sense. For example, open COI and return to the Start Page – the message "Registering new task: Render overview" appears in the log. Detailed scenario:

1. Open UGENE.
2. Open the Log View if it's not already open (press Alt+3 or Opt+3).
3. Enable task logging:
   1. Right-click inside the Log View->"Settings".
      The "Application Settings" dialog appears.
   2. Check the checkbox at the intersection of the "Tasks" row and the "DETAILS" column.
   3. Click "OK" to confirm.
4. Open COI.aln:
   1. Press Ctrl+O (Cmd+O) ("Open").
      The "Select files to open" dialog appears.
   2. Choose Unipro UGENE/data/samples/CLUSTALW/COI.aln.
      The AE appears.
5. Clear the log for the purity of the experiment: right-click inside the Log View->"Clear log".
6. Press Ctrl+Tab (Cmd+Tab) to go from the "COI" window to the Start Page.
   Current state: log message: [DETAILS][13:31] Registering new task: Render overview.
   Expected: no such message.