Resolve "bad value in images.txt release artifact"

Package Merge Request

Package Changes

remove registry:2 from tests/images.txt these get added to the images.txt release artifact by the bigbang_additional_images script

For Issue

Closes #2270 (closed)

Upgrade Notices

"N/A"

tests/images.txt

-registry:2
 registry1.dso.mil/ironbank/big-bang/base:2.1.0
 registry1.dso.mil/ironbank/big-bang/utilities:1.0.3
 registry1.dso.mil/ironbank/opensource/kubernetes-1.21/kubectl:v1.21.14