Fix circular traceplot warnings and title

[agustinaarroyuelo]

Description

When plotting circular variables with plot_trace the circular subplot title overlaps with the x tick labels. I also fixed repeating warnings derived from changing of tick locations.

On master:

This PR:

Checklist

• Follows official PR format
• Includes a sample plot to visually illustrate the changes (only for plot-related functions)
• Code style correct (follows pylint and black guidelines)
• Changes are listed in changelog

[codecov]

Codecov Report

Merging #1517 (12f5e61) into master (90313a1) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1517   +/-   ##
=======================================
  Coverage   91.76%   91.77%           
=======================================
  Files         105      105           
  Lines       11322    11330    +8     
=======================================
+ Hits        10390    10398    +8     
  Misses        932      932           

Impacted Files	Coverage Δ
arviz/plots/backends/matplotlib/kdeplot.py	98.85% <100.00%> (+0.04%)	⬆️
arviz/plots/backends/matplotlib/traceplot.py	98.84% <100.00%> (+0.03%)	⬆️
arviz/data/io_pyro.py	97.35% <0.00%> (ø)
arviz/data/io_emcee.py	98.33% <0.00%> (ø)

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