Vectorize metric computation

[Mr-Geekman]

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?

Proposed Changes

Look #1345.

Closing issues

Closes #1345.

[codecov-commenter]

Codecov Report

Merging #1347 (a40a26a) into master (d23ec9d) will increase coverage by 0.03%.
The diff coverage is 98.37%.

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@@            Coverage Diff             @@
##           master    #1347      +/-   ##
==========================================
+ Coverage   89.13%   89.17%   +0.03%     
==========================================
  Files         204      204              
  Lines       12687    12746      +59     
==========================================
+ Hits        11309    11366      +57     
- Misses       1378     1380       +2     

Files Changed	Coverage Δ
etna/metrics/base.py	94.82% <93.10%> (-1.10%)	⬇️
etna/metrics/__init__.py	100.00% <100.00%> (ø)
etna/metrics/functional_metrics.py	91.52% <100.00%> (+6.23%)	⬆️
etna/metrics/intervals_metrics.py	98.36% <100.00%> (+0.08%)	⬆️
etna/metrics/metrics.py	100.00% <100.00%> (ø)
etna/pipeline/base.py	95.71% <100.00%> (+0.01%)	⬆️

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[github-actions]

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