Fix ansible-test coverage stub memory usage. (#53652)

Split coverage stub files into multiple parts based on the number
of lines in files included in each stub. This will keep memory usage
down to avoid hanging on Shippable.

test/utils/shippable/shippable.sh

@@ -90,6 +90,8 @@ function cleanup
             for file in test/results/reports/coverage=*.xml; do
                 flags="${file##*/coverage=}"
                 flags="${flags%.xml}"
+                # remove numbered component from stub files when converting to tags
+                flags="${flags//stub-[0-9]*/stub}"
                 flags="${flags//=/,}"
                 flags="${flags//[^a-zA-Z0-9_,]/_}"