Change test suite notify script to convert email list to a single line.

[brugger1]

Description

I changed the logic in the visit-notify-test-failure to generate the email recipient list as a single line where the recipients are space separated. Previously, each email recipient was separated by a newline. Since the list gets passed to sendmail on the command line this seems like the right thing to do.

Type of change

• [X] Bug fix~~

How Has This Been Tested?

I tested the script on poodle using the results from last nights test suite run.

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• Please perform a self-review of your code before submitting a PR and asking others to review it.
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Checklist:

• [X] I have commented my code where applicable.~~
• [ ] I have updated the release notes.
• [ ] I have made corresponding changes to the documentation.
• [ ] I have added debugging support to my changes.
• [ ] I have added tests that prove my fix is effective or that my feature works.
• [ ] I have confirmed new and existing unit tests pass locally with my changes.
• [ ] I have added new baselines for any new tests to the repo.
• [ ] I have NOT made any changes to protocol or public interfaces in an RC branch.