[tests] compare_outputs's AssertionError can be massive

[zacharyburnett]

If the fits diff has a lot of lines, that is all pushed into the AssertionError and printed into the pytest log. This can make the test log thousands of lines long; is it possible to summarize this into a simple line count?

drizzlepac/tests/resources.py

Line 212 in d345a84

raise AssertionError(os.linesep + creature_report)

https://github.com/spacetelescope/RegressionTests/actions/runs/10514121938/job/29131353758#step:29:37022

[stscijgbot-hstdp]

This issue is tracked on JIRA as HLA-1316.

[zacharyburnett]

useful in https://github.com/spacetelescope/RegressionTests/pull/122