Test.detect_unbound_args reports cases that are reasonable and harmless

[LilithHafner]

If the unbound static parameter is not used in the function body, then it should not get reported by detect_unbound_args. There are perfectly valid functions that don't use their static parameters. For example:

julia> module Mod
           f(x::NTuple{<:Any, T}, y::NTuple{<:Any, T}) where T = (x..., y...)
       end
Main.Mod

julia> Test.detect_unbound_args(Mod)
[1] f(x::NTuple{var"#s5", T} where var"#s5", y::NTuple{var"#s4", T} where var"#s4") where T @ Main.Mod REPL[14]:2

julia> Mod.f((1,2),(3,4))
(1, 2, 3, 4)

julia> Mod.f((1,2),(3,4.0))
ERROR: MethodError: no method matching f(::Tuple{Int64, Int64}, ::Tuple{Int64, Float64})
The function `f` exists, but no method is defined for this combination of argument types.

Closest candidates are:
  f(::NTuple{var"#s5", T} where var"#s5", ::NTuple{var"#s4", T} where var"#s4") where T
   @ Main.Mod REPL[14]:2

Stacktrace:
 [1] top-level scope
   @ REPL[17]:1

julia> Mod.f((),())
()

This causes spurious test failures in #54494