chore(number_theory/lucas_lehmer): remove `has_to_pexpr` instances (#14905)
chore(number_theory/lucas_lehmer): remove `has_to_pexpr` instances (#14905)

These instances are sort of out-of-place, and aren't really needed anyway.
We already use the more verbose ``%%`(n)`` notation elsewhere in mathlib, which as an operation makes more conceptual sense.


Until #14901 these two instances were just special cases of `has_reflect.has_to_pexpr`. While unlike that instance these two instances are not diamond-forming, they're unecessary special cases that make antiquoting harder to understand.





leanprover-community/mathlib,leanprover-community/mathlib