Add ability to update rate limiter

[black-adder]

Signed-off-by: Won Jun Jang wjang@uber.com

Which problem is this PR solving?

• The current way the rate limiting sampler is updated involves the sampler being reconstructed; this has the unfortunate side effect of the balance being reinitialized to full which will generate a new sample. If you are updating thousands of instances with a new rate limiting rate, this will generate thousands of new traces. This PR adds the ability to update the rate limiter so that the proportional balance is retained on update.

cf. jaegertracing/jaeger-client-go#320

[codecov[bot]]

Codecov Report

Merging #17 into master will increase coverage by 0.19%. The diff coverage is 100%.

@@             Coverage Diff              @@
##             master      #17      +/-   ##
============================================
+ Coverage     84.77%   84.96%   +0.19%     
- Complexity      608      618      +10     
============================================
  Files            94       94              
  Lines          2410     2428      +18     
  Branches        271      271              
============================================
+ Hits           2043     2063      +20     
+ Misses          276      275       -1     
+ Partials         91       90       -1

Impacted Files	Coverage Δ	Complexity Δ
...r/jaeger/samplers/GuaranteedThroughputSampler.java	88.88% <100%> (ø)	7 <0> (ø)	:arrow_down:
.../com/uber/jaeger/samplers/RateLimitingSampler.java	82.6% <100%> (+15.94%)	10 <5> (+4)	:arrow_up:
...c/main/java/com/uber/jaeger/utils/RateLimiter.java	100% <100%> (ø)	8 <6> (+3)	:arrow_up:
.../uber/jaeger/samplers/RemoteControlledSampler.java	86.53% <100%> (+0.67%)	23 <3> (+3)	:arrow_up:

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