Remove yaml-based config option for Cobra binaries

[castelblanque]

Summary In some Cobra commands, if no specific config file is provided, a fixed file name is looked up in the home folder. This is something inherited from old code and not used. Remove it consistently across all binaries.

Some examples:

• Apprepository controller
• Asset syncer

Acceptance criteria All unused looked-up config files in Cobra commands are deleted

Additional context This is something that was found while removing Kubeops. For example, looked up filenames in the examples above are still .kubeops.