Revert "Fix failing event meter tests (#1707)"

This reverts commit b7b5a45.

src/Concerns/ManagesUsageBilling.php

@@ -59,7 +59,7 @@ public function meterEventSummaries(string $meterId, array $options = [], array
     {
         $this->assertCustomerExists();
 
-        $startTime = $options['start_time'] ?? 1;
+        $startTime = $options['start_time'] ?? $this->created_at->timestamp;
 
         $endTime = $options['end_time'] ?? time();