Removing path and line number from warnings.

[devin-petersohn]

• Declutters the warning message so the message is easier to see
• Removes the warnings.warn(message) from the message as well.
• Difference between old and new shown below:

Previous:

/Users/DevinPetersohn/software_builds/modin/modin/error_message.py:32: UserWarning: `cov` defaulting to pandas implementation.
To request implementation, send an email to feature_requests@modin.org.
  warnings.warn(message)

This commit:

UserWarning: `cov` defaulting to pandas implementation.
To request implementation, send an email to feature_requests@modin.org.

• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• passes black --check modin/

[AmplabJenkins]

Merged build finished. Test PASSed.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
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Test PASSed.

[AmplabJenkins]

Merged build finished. Test PASSed.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Modin-PRB/405/
Test PASSed.

[AmplabJenkins]

Merged build finished. Test PASSed.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Modin-Performance-PRB/345/
Test PASSed.

[AmplabJenkins]

Merged build finished. Test PASSed.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Modin-PRB/406/
Test PASSed.

[AmplabJenkins]

Merged build finished. Test PASSed.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Modin-PRB/474/
Test PASSed.

[codecov]

Codecov Report

Merging #447 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #447      +/-   ##
==========================================
+ Coverage   83.23%   83.24%   +0.01%     
==========================================
  Files          33       33              
  Lines        4498     4501       +3     
==========================================
+ Hits         3744     3747       +3     
  Misses        754      754

Impacted Files	Coverage Δ
modin/__init__.py	100% <100%> (ø)	⬆️

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