Upgrade Hystrix to 1.5.18

[tinexw]

Hystrix 1.5.11 was re-released as 1.5.18, s. Netflix/Hystrix#1891 and https://github.com/Netflix/Hystrix/releases/tag/v1.5.18

This PR replaces #3281

[codecov-io]

Codecov Report

Merging #3288 into 2.0.x will increase coverage by 0.04%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##              2.0.x    #3288      +/-   ##
============================================
+ Coverage     66.14%   66.19%   +0.04%     
- Complexity     1473     1476       +3     
============================================
  Files           182      182              
  Lines          6877     6877              
  Branches        840      840              
============================================
+ Hits           4549     4552       +3     
  Misses         2014     2014              
+ Partials        314      311       -3

Impacted Files	Coverage Δ	Complexity Δ
...x/security/SecurityContextConcurrencyStrategy.java	77.77% <0%> (+16.66%)	8% <0%> (+3%)	⬆️

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