Bug 448572
Do not log cancelled transaction exceptions in error log.

Fixed logging issues mentioned in
https://bugs.eclipse.org/bugs/show_bug.cgi?id=448572

Change-Id: I875cefc290646c5e26c4aa8866668e3fb639728b
Reviewed-on: https://git.eclipse.org/r/35958
Reviewed-by: Oli Schmid <oliver.schmid@bsiag.com>
Tested-by: Judith Gull <jgu@bsiag.com>