fix(relay-server): mask secret values in the invalid-value list

The Keys section runs every value through displayValue, which prints <set>
for a name that looks like a credential. The Invalid values section printed
the raw text instead.

Nothing leaks today: an issue is only recorded when a boolean or integer
fails to parse, and no credential is either. But the two lists are read the
same way, and a report that masks a secret in one place and prints it in
another is one numeric credential away from pasting it into a bug thread.

Author: rabbitson87

cmd/relay-server/config.go

@@ -483,7 +483,7 @@ func writeConfigReport(w io.Writer, cfg relayServerConfig, entries []envFileEntr
 	if issues := utils.EnvIssues(); len(issues) > 0 {
 		fmt.Fprintln(w, "\nInvalid values")
 		for _, issue := range issues {
-			fmt.Fprintf(w, "  %s=%s  %s\n", issue.Name, issue.Value, issue.Problem)
+			fmt.Fprintf(w, "  %s=%s  %s\n", issue.Name, displayValue(issue.Name, issue.Value), issue.Problem)
 		}
 	}
 }