[Patch] Small fixes for unit tests

[michael2402]

This is a collection of small fixes to make (more) unit tests pass. Most notably the following bugs are fixed:

• Unit tests assume Europe/Berlin timezone
• PreferencesTest assumed you use josm_test as user.
• Remove Main.map.[mapView.]repaint() calls after command execution or when that layer can be invalidated.
• Fix GpxTrack returning the wrong max time if the latest node is not the last one.
• Set logLevel to default for all tests
• AutosaveTaskTest does not create an endless list of warnings any more - 5 are enough to test that.
• Fix Commmand triggering the selection change in the active data set. It triggers in the edited data set now.

A more detailed version of the changes can be seen here:
​https://github.com/michaelzangl/josm/commits/test-do-not-call-map-repaint