fixes [Bug]: imagePullSecrets is not set for agent DaemonSet #2210

[antoniomerlin]

Resolve #2210 Modify ImagePullSecrets input in agent.go definition to accept imagePullSecrets defined under agent for daemonset strategy. Verified the changes by running TestAgentImagePullSecrets test in agent_test.go and also modified the spec referencd for ImagePullSecrets test.

Checklist

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

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 87.71%. Comparing base (2482014) to head (97afe37).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #2563 +/- ## ======================================= Coverage 87.71% 87.71% ======================================= Files 102 102 Lines 7308 7308 ======================================= Hits 6410 6410 Misses 701 701 Partials 197 197 ```

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[iblancasa]

Thanks @antoniomerlin for your PR!