eth/catalyst: always reset timer after sealing error (#33146)

The periodic sealing loop failed to reset its timer when sealBlock
returned an error, causing the timer to never fire again and effectively
halting block production in developer periodic mode after the first
failure. This is a bug because the loop relies on the timer to trigger
subsequent sealing attempts, and transient errors (e.g., pool races or
chain rewinds) should not permanently stop the loop. The change moves
timer.Reset after the sealing attempt unconditionally, ensuring the loop
continues ticking and retrying even when sealing fails, which matches
how other periodic timers in the codebase behave and preserves forward
progress.

eth/catalyst/simulated_beacon.go

@@ -280,9 +280,8 @@ func (c *SimulatedBeacon) loop() {
 		case <-timer.C:
 			if err := c.sealBlock(c.withdrawals.pop(10), uint64(time.Now().Unix())); err != nil {
 				log.Warn("Error performing sealing work", "err", err)
-			} else {
-				timer.Reset(time.Second * time.Duration(c.period))
 			}
+			timer.Reset(time.Second * time.Duration(c.period))
 		}
 	}
 }