finish deprecation of merge(::Callable ..) (#60027)

fixup to #59775

closes #59990

Author: adienes

base/abstractdict.jl

@@ -362,17 +362,13 @@ merge(d::AbstractDict, others::AbstractDict...) =
 """
     mergewith(combine, d::AbstractDict, others::AbstractDict...)
     mergewith(combine)
-    merge(combine, d::AbstractDict, others::AbstractDict...)
 
 Construct a merged collection from the given collections. If necessary, the
 types of the resulting collection will be promoted to accommodate the types of
 the merged collections. Values with the same key will be combined using the
 combiner function.  The curried form `mergewith(combine)` returns the function
 `(args...) -> mergewith(combine, args...)`.
 
-Method `merge(combine::Union{Function,Type}, args...)` as an alias of
-`mergewith(combine, args...)` is still available for backward compatibility.
-
 !!! compat "Julia 1.5"
     `mergewith` requires Julia 1.5 or later.
 
@@ -405,8 +401,6 @@ Dict{Any, Any} with 1 entry:
 mergewith(combine, d::AbstractDict, others::AbstractDict...) =
     mergewith!(combine, _typeddict(d, others...), others...)
 mergewith(combine) = (args...) -> mergewith(combine, args...)
-merge(combine::Callable, d::AbstractDict, others::AbstractDict...) =
-    merge!(combine, _typeddict(d, others...), others...)
 
 promoteK(K) = K
 promoteV(V) = V