scplan: unredact logs for unable to make progress error

We have seen this error in tests and Sentry reports. The details for the
error do not show up when logs are redacted, so this change makes the
details appear in the AssertionError itself. This also makes stageBuilder
implement redact.SafeFormatter so that the error is formatted safely.

Release note: None

Author: rafiss

pkg/sql/schemachanger/scplan/internal/scstage/build.go

@@ -269,9 +269,10 @@ func buildPostCommitStages(bc buildContext, bs buildState) (stages []Stage) {
 			var trace []string
 			bs.trace = &trace
 			sb = bc.makeStageBuilder(bs)
-			panic(errors.WithDetailf(
-				errors.AssertionFailedf("unable to make progress"),
-				"terminal state:\n%s\nrule trace:\n%s", sb, strings.Join(trace, "\n")))
+			panic(errors.AssertionFailedf(
+				"unable to make progress\nterminal state:\n%v\nrule trace:\n%s",
+				sb, redact.SafeString(strings.Join(trace, "\n")),
+			))
 		}
 		build(sb)
 	}
@@ -728,15 +729,22 @@ func (sb stageBuilder) hasAnyNonRevertibleOps() bool {
 
 // String returns a string representation of the stageBuilder.
 func (sb stageBuilder) String() string {
-	var str strings.Builder
+	return redact.StringWithoutMarkers(sb)
+}
+
+// SafeFormat implements redact.SafeFormatter.
+func (sb stageBuilder) SafeFormat(p redact.SafePrinter, verb rune) {
 	for _, t := range sb.current {
-		str.WriteString(" - ")
-		str.WriteString(screl.NodeString(t.n))
-		str.WriteString("\n")
+		p.SafeString(" - ")
+		if err := screl.FormatNode(p, t.n); err != nil {
+			p.UnsafeString(screl.NodeString(t.n))
+		}
+		p.SafeString("\n")
 	}
-	return str.String()
 }
 
+var _ redact.SafeFormatter = stageBuilder{}
+
 // computeExtraOps generates extra operations to decorate a stage with.
 // These are typically job-related.
 //