Issue 4495 Remove unnecessary #{ .. #} constructs from satb template

Issue 4495 Remove unnecessary #{ .. #} constructs from satb template

Either because they were never needed or because the resolution
of Issue 4421 (Make music functions callable from Scheme) now
permits their removal.

Note: not all such constructs have been removed, even though their
removal is possible, since in these cases removal would reduce clarity.

Also tidy up conditional clauses.