Remove unnecessary UPDATE commands to assign explicit ACLs to functions

and PL languages during initdb.  The default permissions for these objects
are the same as what we were assigning anyway, so there is no need to
expend space in the catalogs on them.  The space cost is particularly
significant in pg_proc's indexes, which are bloated by about a factor of 2
by the full-table update, and can never really recover the space.
initdb not forced, since the change has no actual impact on behavior.