OperationName is not fully overridable

[grobertson-data]

Description

#2040 made it so if the operationName was overridden then in wouldn't have sanitize called, and so '_'or '$' wouldn't be removed.
#3693 has removed this behaviour and now sanitize is called on the operationName returned.

Output client

fetch

Expected behavior

A custom operationName is preserved

Actual behavior

Underscores are stripped out

Additional context

No response

[melloware]

Cc @aqeelat

[aqeelat]

Will fix soon.