Miscellaneous fixes (#22779)

* block ffmpeg args in custom exports for non-admin users only

* prune expired reconnect timestamps periodically in watchdog loop

reconnect timestamps were only pruned when a new reconnect
occurred. This meant a single reconnect would persist in the count indefinitely instead of expiring after 1 hour

* formatting

frigate/video/ffmpeg.py

@@ -471,8 +471,16 @@ class CameraWatchdog(threading.Thread):
                     p["cmd"], self.logger, p["logpipe"], ffmpeg_process=p["process"]
                 )
 
-            # Update stall metrics based on last processed frame timestamp
+            # Prune expired reconnect timestamps
             now = datetime.now().timestamp()
+            while (
+                self.reconnect_timestamps and self.reconnect_timestamps[0] < now - 3600
+            ):
+                self.reconnect_timestamps.popleft()
+            if self.reconnects:
+                self.reconnects.value = len(self.reconnect_timestamps)
+
+            # Update stall metrics based on last processed frame timestamp
             processed_ts = (
                 float(self.detection_frame.value) if self.detection_frame else 0.0
             )