utility-tasks.bbclass: Move distro related tasks to distrodata.bbclass
Most of the d.keys() used in file parsing are variables in
distro_tracking_fields.inc, which are not used in normal build.
Therefore remove the inclusion of distro_tracking_fields.inc from
poky.conf. Besides, move distro related tasks to distrodata.bbclass,
which includes that tracking field file.
By this change, the file parsing time could save about 25%.
