Change np.percentile to np.nanpercentile in loggers.base

[Mr-Geekman]

IMPORTANT: Please do not create a Pull Request without creating an issue first.

Before submitting (must do checklist)

• Did you read the contribution guide?
• Did you update the docs? We use Numpy format for all the methods and classes.
• Did you write any new necessary tests?
• Did you update the CHANGELOG?

Type of Change

• Examples / docs / tutorials / contributors update
• Bug fix (non-breaking change which fixes an issue)
• Improvement (non-breaking change which improves an existing feature)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Proposed Changes

#482.

Related Issue

#482.

Closing issues

Closes #482.

[codecov-commenter]

Codecov Report

Merging #483 (1a329a4) into master (c1f49ed) will decrease coverage by 34.28%.
The diff coverage is 0.00%.

@@             Coverage Diff             @@
##           master     #483       +/-   ##
===========================================
- Coverage   87.83%   53.55%   -34.29%     
===========================================
  Files         115      115               
  Lines        5452     5452               
===========================================
- Hits         4789     2920     -1869     
- Misses        663     2532     +1869     

Impacted Files	Coverage Δ
etna/loggers/base.py	67.60% <0.00%> (-28.17%)	⬇️
etna/commands/__init__.py	0.00% <0.00%> (-100.00%)	⬇️
etna/commands/backtest_command.py	0.00% <0.00%> (-96.43%)	⬇️
etna/commands/forecast_command.py	0.00% <0.00%> (-92.00%)	⬇️
etna/commands/__main__.py	0.00% <0.00%> (-87.50%)	⬇️
etna/commands/resolvers.py	0.00% <0.00%> (-80.00%)	⬇️
etna/analysis/outliers/density_outliers.py	22.44% <0.00%> (-75.52%)	⬇️
etna/transforms/timestamp/time_flags.py	26.02% <0.00%> (-73.98%)	⬇️
etna/transforms/timestamp/fourier.py	27.08% <0.00%> (-72.92%)	⬇️
etna/transforms/feature_selection/filter.py	28.57% <0.00%> (-71.43%)	⬇️
... and 66 more

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[iKintosh]

This makes life easier. Thanks!