Removed duplicate instances of str().length()

[AnikaAChowdhury]

Submission Checklist

• Run unit tests: ./runTests.py src/test/unit
• Run cpplint: make cpplint
• Declare copyright holder and open-source license: see below

Summary

This fixes #2577 which is cleaning up code instances that has .str().length() for logger.info(). This cleans up a lot of "if (msg.str().length() > 0)" instances from the code block that follows
if (msg.str().length() > 0)
logger.info(msg);
patterns. However, there are still a lot of instances "if (msg.str().length() > 0)" left because it was connected with another logger implementation beside logger.info(). Therefore, some of the instances of that could not be removed.

Intended Effect

Removes a lot of duplicate codes.

How to Verify

Need to run tests on the existing testing library (In Progress).

Side Effects

Followed @WardBrian's suggestions.

Documentation

Copyright and Licensing

Please list the copyright holder for the work you are submitting (this will be you or your assignee, such as a university or company):

By submitting this pull request, the copyright holder is agreeing to license the submitted work under the following licenses:

• Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
• Documentation: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)