teardown_sentry_test helper should clear global even processors too

[st0012]

Closes #2051

When resetting the test environment with the teardown_sentry_test helper, global event processors should be cleared too.

(I also made sentry-ruby's tests not fail fast as they're quite flaky at times due to dependencies, request issues...etc.)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.66%. Comparing base (89f371f) to head (554a439).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2342   +/-   ##
=======================================
  Coverage   98.66%   98.66%           
=======================================
  Files         205      205           
  Lines       13488    13493    +5     
=======================================
+ Hits        13308    13313    +5     
  Misses        180      180           

Components	Coverage Δ
sentry-ruby	99.03% <100.00%> (+<0.01%)	⬆️
sentry-rails	97.41% <ø> (ø)
sentry-sidekiq	97.01% <ø> (ø)
sentry-resque	96.79% <ø> (ø)
sentry-delayed_job	98.92% <ø> (ø)
sentry-opentelemetry	100.00% <ø> (ø)

Files	Coverage Δ
sentry-ruby/lib/sentry/test_helper.rb	100.00% <100.00%> (ø)
sentry-ruby/spec/sentry/test_helper_spec.rb	100.00% <100.00%> (ø)

[gi]

@st0012 I don't think that theteardown_sentry_test method should touch the global event processors.

1. The setup_sentry_test method does not touch them, so why should we assume that the teardown method should?
2. Any global event processors setup by the application are unfortunately cleared. This method is suggested to be run after every example/test, so this teardown behavior would necessitate running the application setup before every test.

Also, this PR does not fix the issue that #2051 describes: Sentry.init does not clear the global event processors. This PR is all about the test helper.

I suggest the issue be reopened or closed as "won't fix" and this PR be reverted.

I filed a bug report just in case you agree after some consideration. Feel free to close if you disagree.