Use JSON-key-order-agnostic assertion on child timeout_policy snapshot

One more MySQL JSON column comparison that was sensitive to key order
on InnoDB — the child call's `timeout_policy` JSON column stores
`execution_timeout_seconds` and `run_timeout_seconds` in the storage
engine's internal order. Swap the literal-array assertSame for
assertSameJsonObject like the rest of the #399 JSON-ordering fixes.

Clears 1 MySQL failure under #399:
  * testCompleteStartsChildWorkflowSnapshotsRetryPolicyAndTimeouts

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: durable-workflow-ops

tests/Feature/V2/V2WorkflowTaskBridgeTest.php

@@ -1922,7 +1922,7 @@ public function testCompleteStartsChildWorkflowSnapshotsRetryPolicyAndTimeouts()
             'backoff_seconds' => [2, 8],
             'non_retryable_error_types' => ['ValidationError'],
         ], $childCall->retry_policy);
-        $this->assertSame([
+        $this->assertSameJsonObject([
             'snapshot_version' => 1,
             'execution_timeout_seconds' => 600,
             'run_timeout_seconds' => 120,