docs(auditlog): generalize two stale XML-doc comments

- AddColumnIfMissing is now shared by ExecutionId and ParentExecutionId;
  drop the ExecutionId-specific tag.
- AuditLogRepository.GetExecutionTreeAsync doc no longer hardcodes the
  MAXRECURSION literal; reference the ExecutionChainMaxDepth const instead.

src/ScadaLink.ConfigurationDatabase/Repositories/AuditLogRepository.cs

@@ -581,8 +581,9 @@ VALUES
     /// and joining <c>edge.ParentExecutionId = chain.ExecutionId</c> to
     /// enumerate every descendant. Recursing over edges rather than raw rows
     /// keeps the recursion one path wide per execution. It is bounded by
-    /// <c>OPTION (MAXRECURSION 32)</c> — corrupt cyclic data raises a
-    /// <see cref="SqlException"/> (msg 530) rather than spinning.
+    /// <c>OPTION (MAXRECURSION ...)</c> at <see cref="ExecutionChainMaxDepth"/>
+    /// — corrupt cyclic data raises a <see cref="SqlException"/> (msg 530)
+    /// rather than spinning.
     /// </para>
     /// <para>
     /// The chain's full execution-id set is every edge's <c>ExecutionId</c>