Don't write Format for Coverage, ClassDef, Single/Alternate/LigatureSubst
Don't write Format for Coverage, ClassDef, Single/Alternate/LigatureSubst

The format values for those are automatically handled in
postRead/preWrite to choose optimal format.  As such, don't write them
in XML.  Reduces noise.

https://github.com/fonttools/fonttools/pull/2236#issuecomment-804523961

fonttools/fonttools,googlefonts/fonttools