spanconfig: improve redaction for spanconfig reconciler error

[rafiss]

These logs show that we might be over-redacting an error when the spanconfig reconciler fails.

AUTO SPAN CONFIG RECONCILIATION job 1115060038728810497: stepping through state failed with unexpected error: reconciliation unsuccessful, failing job
(1) forced error mark
  | ‹×›
  | github.com/cockroachdb/errors/withstack/*withstack.withStack::
Wraps: (2) attached stack trace
  -- stack trace:
  | github.com/cockroachdb/cockroach/pkg/spanconfig/spanconfigjob.(*resumer).Resume
  | 	pkg/spanconfig/spanconfigjob/job.go:196
  | github.com/cockroachdb/cockroach/pkg/jobs.(*Registry).stepThroughStateMachine.func2
  | 	pkg/jobs/registry.go:1720
  | github.com/cockroachdb/cockroach/pkg/jobs.(*Registry).stepThroughStateMachine
  | 	pkg/jobs/registry.go:1721
  | github.com/cockroachdb/cockroach/pkg/jobs.(*Registry).runJob
  | 	pkg/jobs/adopt.go:410
  | github.com/cockroachdb/cockroach/pkg/jobs.(*Registry).resumeJob.func1
  | 	pkg/jobs/adopt.go:263
  | github.com/cockroachdb/cockroach/pkg/util/stop.(*Stopper).RunAsyncTaskEx.func2
  | 	pkg/util/stop/stopper.go:500
  | runtime.goexit
  | 	src/runtime/asm_amd64.s:1700
Wraps: (3) reconciliation unsuccessful, failing job
Error types: (1) *markers.withMark (2) *withstack.withStack (3) *errutil.leafError

We should check to see if the forced error mark ‹×› includes any useful information that we should not be redacting. Do we log the actual error in any of the surrounding logs?

Jira issue: CRDB-55414

Epic CRDB-55074

[spilchen]

When we retry reconciler errors, we do log them here:

cockroach/pkg/spanconfig/spanconfigjob/job.go

Line 189 in bc1b6d6

log.Dev.Errorf(ctx, "reconciler failed with %v, retrying...", err)

From the datadog logs, I see this:

reconciler failed with type ‹×› does not exist, retrying...

This is hit quite a few times:
https://us5.datadoghq.com/logs?query=source%3Acockroachdb%20env%3Aproduction%20AND%20%40tenant_id%3A16440%20%40friendly_id%3Acrl-prod-j77%20%28%22reconciler%20failed%20with%22%20OR%20%22reconciliation%20unsuccessful%22%29&cols=host%2Cservice&fromUser=true&messageDisplay=inline&refresh_mode=paused&storage=flex_tier&stream_sort=time%2Cdesc&viz=stream&from_ts=1760356800000&to_ts=1760364000000&live=false

[blathers-crl]

Based on the specified backports for linked PR #155463, I applied the following new label(s) to this issue: branch-release-25.4. Please adjust the labels as needed to match the branches actually affected by this issue, including adding any known older branches.

_{🦉 Hoot! I am a Blathers, a bot for CockroachDB. My owner is dev-inf.}