s3tables, iceberg: log client refusals at V(1), not ERROR (#11896)

* s3tables, iceberg: log client refusals at V(1), not ERROR

Requests the S3 Tables and Iceberg REST APIs correctly refuse with a 4xx
(access denied, not authorized, no such namespace, already exists, not
empty, a commit conflict) were logged with glog.Errorf, so a client probing
for what it may do, or retrying an optimistic commit, filled the ERROR log
and hid real faults from anyone alerting on it.

- s3tables: HandleRequest wraps the ResponseWriter in a statusRecorder (with
  Unwrap for http.ResponseController) and logs a handler error by the status
  it answered: 4xx at V(1) as "<op> refused (<status>)", 5xx or no status at
  ERROR as before.
- s3tables: the "handleCreateNamespace called" trace moves from ERROR to V(3).
- iceberg: writeManagerError's mapping is split into classifyManagerError,
  shared with a new logManagerError that logs 4xx-mapped errors at V(1) and
  everything else at ERROR; used by CreateNamespace, CommitTable and
  CommitTransaction.
- storage: loading a remote-tier volume logged
  "readSuperBlock remote volume N: <nil>" at ERROR even when the read
  succeeded; it is now logged only when there is an error.

Tests: TestRequestRefusedWith4xxIsNotLoggedAsError, TestLogRequestErrorByStatus,
TestStatusRecorderKeepsTheFirstStatus, TestStatusRecorderUnwrapsForResponseController,
TestNoTraceLoggedAtErrorLevel (fails on master on the CreateNamespace trace),
TestLogManagerErrorRefusalsAreNotErrors, TestRemoteSuperBlockLogOnlyOnError.

* s3tables: do not log a malformed CreateNamespace body at ERROR

handleCreateNamespace logged a body it could not decode at ERROR before
answering 400; the dispatcher already logs that refusal once at V(1).

Also drop statusRecorder.Flush: it made the recorder an http.Flusher even
over a writer that cannot flush, so http.NewResponseController reported
success instead of ErrNotSupported. Unwrap already lets the controller
reach the wrapped writer.

* iceberg: require exactly one log line per classified manager error

The test accepted a refusal that produced no log, or both logs. Require
one V(1) refusal and no ERROR for a 4xx, and the reverse for a fault.

---------

Co-authored-by: Javier de la Torre <jatorre@lakehousebox.com>

weed/s3api/s3tables/handler_namespace.go

@@ -36,10 +36,9 @@ func (h *S3TablesHandler) mayRepairOwnerlessBucket(r *http.Request) bool {
 
 // handleCreateNamespace creates a new namespace in a table bucket
 func (h *S3TablesHandler) handleCreateNamespace(w http.ResponseWriter, r *http.Request, filerClient FilerClient) error {
-	glog.Errorf("S3Tables: handleCreateNamespace called")
+	glog.V(3).Infof("S3Tables: handleCreateNamespace called")
 	var req CreateNamespaceRequest
 	if err := h.readRequestBody(r, &req); err != nil {
-		glog.Errorf("S3Tables: handleCreateNamespace failed to read request body: %v", err)
 		h.writeError(w, http.StatusBadRequest, ErrCodeInvalidRequest, err.Error())
 		return err
 	}