Revert "Bug 573595 - AutoBuildJob following a search and replace might
run as system job"

This caused lot of JDT core test fails, see bug 574098

This reverts commit 4bca749b780c2a9221c9614490e636fe5d2de99b.

Change-Id: Iae221bc4dd5d40143ac5cc6c3add70021264152e
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.resources/+/181688
Tested-by: Platform Bot <platform-bot@eclipse.org>
Reviewed-by: Andrey Loskutov <loskutov@gmx.de>