[ upstream commit e2b17ec ]

[ backporter's notes: adapted the path as the v1.16 tree still used
  logrus rather than slog; adapted the unit test to reflect the
  different output format (most notably, the lowercase keywords and
  the different key-values pairs order). ]

Controller runtime emits an error log whenever a reconcile function
terminates with an error. However, reconciliation errors are harmless
in most cases, as the subsequent iteration will normally pull the
updated state and succeed. Still, this breaks the Cilium's assumption
that error logs are emitted only in case of serious conditions,
causing potential user confusion, as well as triggering the error
logs check run as part of the E2E tests.

Let's introduce a wrapper responsible for converting "Reconciler error"
messages to info level logs, when the returned error is likely to be
transient. We specifically check the error type to avoid hiding unexpected
ones, although more types could be added in the future if deemed helpful.

Signed-off-by: Marco Iorio <marco.iorio@isovalent.com>