toaster: fix target package information

Toaster needs to record information about packages
installed on a built target image, and dependencies
between these packages.

This patch fixes a bug where the variable from the
server wasn't read correctly leading which caused
the buildhistory to not be processed correctly.

Additionally, two display issues in the package table
were fixed, issues that lead to package information
being displayed incorrectly.

    [YOCTO #5197]

Signed-off-by: Alexandru DAMIAN <alexandru.damian@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>