toaster: api / project Cancel any in progress builds before project delete

toaster: api / project Cancel any in progress builds before project delete

Before we finally delete any project make sure we send the cancel command to
any in-progress builds. This ensures that an inaccessible build doesn't block
up the system and that we don't get errors after deletion.

[YOCTO #10289]

Signed-off-by: Michael Wood <michael.g.wood@intel.com>
Signed-off-by: bavery <brian.avery@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>