Enhance zypper install error messages.

[ycedres]

What does this PR do?

Adds stdout to the error message if zypper install returns with an error code and there is no information on standard error.

What issues does this PR fix or reference?

None.

Previous Behavior

If zypper install returns with an error code and there is no output on standard error, tells the user to check zypper logs.

New Behavior

If zypper install returns with an error code and there is no output on standard error, uses standard output to give more information to the user.

Merge requirements satisfied?

• Docs
• Changelog - https://docs.saltproject.io/en/master/topics/development/changelog.html
• Tests written/updated

Commits signed with GPG?

Yes

Please review Salt's Contributing Guide for best practices.

See GitHub's page on GPG signing for more information about signing commits with GPG.

[welcome]

Hi there! Welcome to the Salt Community! Thank you for making your first contribution. We have a lengthy process for issues and PRs. Someone from the Core Team will follow up as soon as possible. In the meantime, here’s some information that may help as you continue your Salt journey.
Please be sure to review our Code of Conduct. Also, check out some of our community resources including:

• Community Wiki
• Salt’s Contributor Guide
• Join our Community Slack
• IRC on LiberaChat
• Salt Project YouTube channel
• Salt Project Twitch channel

There are lots of ways to get involved in our community. Every month, there are around a dozen opportunities to meet with other contributors and the Salt Core team and collaborate in real time. The best way to keep track is by subscribing to the Salt Community Events Calendar.
If you have additional questions, email us at [email protected]. We’re glad you’ve joined our community and look forward to doing awesome things with you!

[ycedres]

Some checks unrelated to the PR keep failing so I will wait some days to try to run them again.

[ycedres]

@krionbsd some checks keep failing on this PR that are apparently unrelated to the changes. I've tried forcing a rerun several times and different checks failed each time. Do you have any idea about what could be happening?

[welcome]

Congratulations on your first PR being merged! 🎉