logger: fix multiple format definitions for multi-instance topics
logger: fix multiple format definitions for multi-instance topics

With https://github.com/PX4/Firmware/pull/12123 all multi-instance topics
lead to repeated format definitions in the ULog file.

acfloria/Firmware,krbeverx/Firmware,krbeverx/Firmware,krbeverx/Firmware,acfloria/Firmware,krbeverx/Firmware,acfloria/Firmware,PX4/Firmware,krbeverx/Firmware,dagar/Firmware,dagar/Firmware,acfloria/Firmware,PX4/Firmware,PX4/Firmware,dagar/Firmware,dagar/Firmware,dagar/Firmware,PX4/Firmware,krbeverx/Firmware,acfloria/Firmware,PX4/Firmware,dagar/Firmware,acfloria/Firmware,PX4/Firmware,dagar/Firmware,PX4/Firmware,krbeverx/Firmware,acfloria/Firmware