Fix Warning log during prepare stage for the Kubernetes executor

What does this MR do?

To avoid the following warning in the job log file

Why was this MR needed?

NA

What's the best way to test this MR?

gitlab-ci

build:
  image:
    name: gcr.io/kaniko-project/executor:v1.9.1-debug
    entrypoint: [""]
  script:
    - ls -alF
    - |
      /kaniko/executor --no-push

config.toml

concurrent = 1
check_interval = 0
log_level = "debug"
shutdown_timeout = 0

[session_server]
  session_timeout = 1800

[[runners]]
  name = ""
  url = "https://gitlab.com/"
  id = 149
  token = "REDACTED"
  token_obtained_at = 2023-02-07T10:29:37Z
  token_expires_at = 0001-01-01T00:00:00Z
  executor = "kubernetes"
  [runners.kubernetes]
    host = ""
    bearer_token_overwrite_allowed = false
    image = "alpine:latest"
    namespace = ""
    namespace_overwrite_allowed = ""
    allowed_pull_policies = ["always", "if-not-present"]
    pull_policy = ["always", "if-not-present"]
    node_selector_overwrite_allowed = ""
    pod_labels_overwrite_allowed = ""
    service_account_overwrite_allowed = ""
    pod_annotations_overwrite_allowed = ""
    [runners.kubernetes.pod_annotations]
      job_name = "$CI_JOB_NAME"
    [runners.kubernetes.pod_security_context]
    [runners.kubernetes.volumes]
    [runners.kubernetes.dns_config]

The job should not display the WARNING: 49 <nil> line

What are the relevant issue numbers?

NA