Dont omit output when script fails

[wenovus]

Previously when the whole script fails the individual models' results were being discarded. This makes debugging more difficult. Now append them to the script stderr output.

See results from https://github.com/openconfig/public/pull/1043

e.g. https://gist.github.com/OpenConfigBot/2b079ba55f45e202440eed488d274d1b, https://gist.github.com/OpenConfigBot/b0961781139bc51fc2d25c15942f2eb2

[github-actions[bot]]

Pull Request Test Coverage Report for Build 7763273478

• -3 of 27 (88.89%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.2%) to 55.307%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
post_results/main.go	24	27	88.89%
<!--	Total:	24	27	88.89%	-->

Totals
Change from base Build 7051208360:	0.2%
Covered Lines:	964
Relevant Lines:	1743

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💛 - Coveralls