Remove hardcoded api key name in sources

[nuclearcat]

As @pawiecz rightfully pointed in other issue we need to reduce technical debt and hardcoded/undocumented behavior . For example: https://github.com/kernelci/kernelci-core/blob/a42e092649ad29ceaaf62fbe1a460e74c7d517f6/kernelci/runtime/kubernetes.py#L41