3102:nodejs-logging-winston: Convert samples test from ava to mocha

[nareshqlogic]

Fixes convert all sample tests from ava to mocha #2865(googleapis/google-cloud-node#2865) (it's a good idea to open an issue first for discussion)

• Tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)

[DominicKramer]

Thank you for opening this PR. For completeness, can you please provide a short summary of why this change is needed for those that don't want to log in to view the link you referenced. Thanks.

[JustinBeckwith]

@DominicKramer this is part of a broad effort to use mocha consistently for all of our tests. This is mine :)

[DominicKramer]

@JustinBeckwith sounds good 👍

[nareshqlogic]

@DominicKramer Thank you for suggestion I will add the description.

[JustinBeckwith]

After the system tests are passing, I'm happy to merge!

[nareshqlogic]

Hi @JustinBeckwith,

Sorry for late reply.
Should we required to pass successfully system-test? as we are working on converting samples test from ava to mocha. Let me correct if I am wrong.

Further when I execute command 'npm run system-test'. I am able to see two test cases are passed successfully that is shown failed in log file and rest required "Stackdriver Error Reporting API has not been used in project 980770916211 before or it is disabled" and my account still not have credentials to enable it. Here is output file attached after running system test from my local window system using nodejs v8.11.3 and please let me know your feedback.
log.txt
.

[DominicKramer]

I think the system test errors are independent of this PR. PR #212 fixes part of the system system tests. I am also working on another PR that fixes the installation tests. When those land, and you rebase, the system tests should pass on this PR.