Convert QualityMetrics/Header.tsx to Functional Component and Header.test.js to RTL

[Parship999]

Which problem is this PR solving?

• Resolves part of [Feature]: Refactor class components to functional components #2610

Description of the changes

• Converted Header.tsx from a class component to a functional component
• Replaced Enzyme tests with RTL in Header.test.js

Checklist

• I have read https://github.com/jaegertracing/jaeger/blob/master/CONTRIBUTING_GUIDELINES.md
• I have signed all commits
• I have added unit tests for the new functionality
• I have run lint and test steps successfully
  • for jaeger: make lint test
  • for jaeger-ui: npm run lint and npm run test

[graphite-app]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.39%. Comparing base (dd65633) to head (3325ab2).
Report is 7 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2859   +/-   ##
=======================================
  Coverage   97.39%   97.39%           
=======================================
  Files         256      256           
  Lines        7975     7975           
  Branches     2084     2009   -75     
=======================================
  Hits         7767     7767           
  Misses        208      208           

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