Add flags with default variables for autoscaling and batch version

[chlunde]

Which problem is this PR solving?

If these valuese are not initialized, the generator code will produce
invalid kubernetes objects when generating manifest files.

In operator mode, the default values were automatically detected.

Fixes #2767

Description of the changes

Set default flag values

How was this change tested?

• go run . generate --cr in.yaml # check apiVersion for CronJob and HPA
• make test

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

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 74.73%. Comparing base (e4536a8) to head (110b03a).

Files with missing lines	Patch %	Lines
pkg/cmd/start/main.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2768      +/-   ##
==========================================
- Coverage   74.74%   74.73%   -0.02%     
==========================================
  Files         124      124              
  Lines       10497    10499       +2     
==========================================
  Hits         7846     7846              
- Misses       2454     2456       +2     
  Partials      197      197              

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