Fixes#1650
A regression was introduced with 3.43.0 when doing pyftsubset --flavor=woff2
and the input font is WOFF 1.0, thus it has a non-None flavorData already
but doesn't define the transformTables attribute.
Also, the TTFont.getGlyphOrder() automatically makes up a dummy
glyph order from the maxp.numGlyphs, we simply need to ensure
'maxp' is decompiled before 'glyf'.
When transforming glyf, the glyf.glyphOrder is guaranteed to
be present (as the glyf table has been already decompiled), so
we don't need to deal with it being missing or incorrect
(hence removed spurious tests).
Using TTFont.getGlyphOrder() would also require to decompile post and cmap tables.
But we don't need the actual glyph names in order to apply the WOFF2 glyf transform.
