backend: Refactor headlamp.go refreshAndCacheNewToken to be shorter

[illume]

This function needs to be shorter to reduce the complexity of it, and make it easier to understand. Perhaps it should be 2 or more functions.

Currently the code turns off the linter for this issue with "//nolint:funlen".

• [ ] refactor the code to make the function short and easier to understand
• See quick start contributing guide on how to get started.
• See backend/cmd/headlamp.go file.
• See backend contributing guide
• To run the linter, make backend-lint
• How to run tests: make backend-test

Related umbrella backend refactoring clean up issue https://github.com/headlamp-k8s/headlamp/issues/855 (other pieces of code have the linter disabled and could also be fixed up, feel free to refactor a different function.)

[CroWzblooD]

Is it still availabl,e I would like to give a try