Update saturation level for AG cameras

With INSTRM-2558, saturation level is now handled each amp separately per region. A few amps are know to show saturation lower than 65535. In the run 23 in June 2025, a couple of data set were taken to analyze the saturation level.

Note that once saturation level is updated, "flat-top" flag will be removed (INSTRM-2586).

The visit=127134 and 127480 are the data.

As noted in INSTRM-2558, Kawanomoto-san kindly looked at the data visit=127134 separately:

• AG2 Left looks saturated around 64200
• AG3 Left looks saturated around 60500
• There doesn't seem bright enough object on AG2 Right and AG4 Left.