ES storage: not logging requests on error

[tmszdmsk]

Which problem is this PR solving?

• Resolves badly formatted logs on stderr #896

Short description of the changes

• Because failed requests buffer can get very big it can make error logs impossible to parse (e.g. by ELK stack) so that it is harder to debug the actual problem.
• badly formatted logs on stderr #896 (comment)

[codecov]

Codecov Report

Merging #901 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #901   +/-   ##
=======================================
  Coverage   99.96%   99.96%           
=======================================
  Files         126      126           
  Lines        6072     6072           
=======================================
  Hits         6070     6070           
  Misses          2        2

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[yurishkuro]

thanks!

[tmszdmsk]

@yurishkuro
np, I was thinking about adding information about #failed requests and #all requests. What do you think about that?