Regression fixed. The log method does not require MessageFormat.
MessageFormat cannot work with empty {}.

Change-Id: I66c5b3a76d77f49d48cba895609813a1d9077a2f
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.ui/+/180832
Reviewed-by: Dirk Fauth <dirk.fauth@googlemail.com>
Reviewed-by: Lars Vogel <Lars.Vogel@vogella.com>
Reviewed-by: Andrey Loskutov <loskutov@gmx.de>
Tested-by: Lars Vogel <Lars.Vogel@vogella.com>