Reduce log level for "Connection not found" event from error to warning for chosen Connections.

[Crowiant]

When Operators from the Kubernetes provider use the default connection ID (kubernetes_default) and the connection hasn't been created manually by a user (or via airflow connections create-default-connection), an ERROR is logged. This situation isn't actually an error for the provider. The KubernetesHook is designed to fall back to cluster-derived credentials if the default connection is not found:

airflow/providers/cncf/kubernetes/src/airflow/providers/cncf/kubernetes/hooks/kubernetes.py

Lines 172 to 184 in b7ea2a6

	def get_connection(cls, conn_id: str) -> Connection:
	"""
	Return requested connection.
	If missing and conn_id is "kubernetes_default", will return empty connection so that hook will
	default to cluster-derived credentials.
	"""
	try:
	return super().get_connection(conn_id) # type: ignore[return-value]
	except AirflowNotFoundException:
	if conn_id == cls.default_conn_name:
	return Connection(conn_id=cls.default_conn_name)
	raise

PR reduces log_level for this provider from ERROR to WARNING.
Closes: #56360

---

^ Add meaningful description above
Read the Pull Request Guidelines for more information.
In case of fundamental code changes, an Airflow Improvement Proposal (AIP) is needed.
In case of a new dependency, check compliance with the ASF 3rd Party License Policy.
In case of backwards incompatible changes please leave a note in a newsfragment file, named {pr_number}.significant.rst or {issue_number}.significant.rst, in airflow-core/newsfragments.

[ashb]

I think we should just remove that log message entirely, it is just noise and will be exposed to tasks as an exception anyway.

Old comment - addressed