Thanks SoCalRacer.
I tried your command but unfortunately, it didn't return anything relevant to Backblaze.
Nevermind though, I found out how to obtain what I needed:
$ defaults read /Library/PreferencePanes/BackblazeBackup.prefPane/Contents/Info CFBundleIdentifier
com.backblaze.BackblazeBackup
I inserted com.backblaze.BackblazeBackup into the Third Party System Preference Panes field, as per my first screenshot, and it worked!: