vault install ember-sinon-qunit

We’ve been seeing this failure a lot lately on CI and recently some flaky client count tests Attempted to wrap now which is already wrapped

Error: Browser timeout exceeded: 10s
Error while executing test: Acceptance | wrapped_token query param functionality: it should authenticate when hitting logout url with wrapped_token when logged out
Stderr: 
 Fontconfig error: No writable cache directories
[0502/143350.692707:INFO:config_dir_policy_loader.cc(118)] Skipping mandatory platform policies because no policy file was found at: /etc/opt/chrome/policies/managed
[0502/143350.712793:INFO:config_dir_policy_loader.cc(118)] Skipping recommended platform policies because no policy file was found at: /etc/opt/chrome/policies/recommended
[0502/143351.025464:WARNING:sandbox_linux.cc(420)] InitializeSandbox() called with multiple threads in process gpu-process.
[0502/143352.637846:WARNING:runtime_features.cc(730)] AttributionReportingCrossAppWeb cannot be enabled in this configuration. Use --enable-features=ConversionMeasurement,AttributionReportingCrossAppWeb in addition.

ember-sinon is deprecated and we should be using ember-sinon-qunit:

Why not simply use sinon alone? sinon does not handle cleanup of ember-qunit tests. While sinon sandboxes itself, it’s up to the user to consistently clean up sinon after each test. ember-sinon-qunit automatically restores sinon’s state to ensure nothing is leaked between tests. All spies/stubs created will be automatically restored to their original methods at the end of each test.