[tests] Expand coverage results

[kcreddy]

Following paths are not covered in the coverage reports for each <package>:

./data_stream/*/lifecycle.yml
./data_stream/*/elasticsearch/ilm/*
./elasticsearch/transform/*
./kibana/tags.yml
./kibana/tag/*
./validation.yml

This leads to low coverage of packages inside PRs and scheduled CI runs.
Example: elastic/integrations#14290 (comment) which has 18% coverage on new code.

Increase coverage on these paths. Alternately add these paths into exclusion list as temporary measure.

[jsoriano]

Adding coverage reports for most of the files in #2831.

For lifecycle management not sure what to do, as I think we are actually not testing this now.