ci-test: exit on error

[thepwagner]

The most important change of the PR is to each ecosystem's script/ci-test scripts, introduced in #3426 . We want these shells to exit on the first non-zero status, not to return the status of their last command.

The previous version of these scripts masked problems:

• Most commonly, the output of rubocop was ignored. I noticed this as style: use consistent indentation for first element #3649 changed rules and passed CI - but produced a diff when auto-applying locally.
• In the python ecosystem, the pylint status was ignored. I fixed a whitespace issue
• In the bundler ecosystem, the status of rspec is ignored - we'd removed some required fixtures and were looking for some fixtures in the wrong place.

Sorry for the meandering scope: it's fixing the CI script to detect problems, then trying to find a minimal resolution to problems that have crept in.

[thepwagner]

In this draft, I expect the go_modules build to fail: I think it had issues the automated fix couldn't resolve, and I wanted to demonstrate lint failures are build failures now.

[mctofu]

nice catch!