Follow up #1469

[st0012]

This PR:

1. Simplifies tests added in Set user to the current scope via sidekiq middleware #1469
2. Adds a changelog entry.

[codecov-commenter]

Codecov Report

Merging #1483 (3129452) into master (79f0453) will increase coverage by 0.54%.
The diff coverage is 100.00%.

❗ Current head 3129452 differs from pull request most recent head 1b96dd6. Consider uploading reports for the commit 1b96dd6 to get more accurate results

@@            Coverage Diff             @@
##           master    #1483      +/-   ##
==========================================
+ Coverage   98.21%   98.76%   +0.54%     
==========================================
  Files         218      123      -95     
  Lines       10471     6624    -3847     
==========================================
- Hits        10284     6542    -3742     
+ Misses        187       82     -105     

Impacted Files	Coverage Δ
...c/sentry/sidekiq/sentry_context_middleware_spec.rb	100.00% <100.00%> (ø)
...iq/lib/sentry/sidekiq/sentry_context_middleware.rb	96.87% <0.00%> (-3.13%)	⬇️
sentry-raven/lib/raven/processor/http_headers.rb
sentry-raven/lib/raven/event.rb
...ntry-raven/spec/raven/processors/post_data_spec.rb
...y-raven/lib/raven/integrations/rails/active_job.rb
...en/lib/raven/integrations/sidekiq/error_handler.rb
sentry-raven/spec/raven/interface_spec.rb
sentry-raven/lib/raven/processor/sanitizedata.rb
sentry-raven/spec/raven/transports/http_spec.rb
... and 87 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 79f0453...1b96dd6. Read the comment docs.