Python: Fix query names that inclde __ (dunder)

Without backticks, the text UNDERSCORE UNDERSCORE eq UNDERSCORE UNDERSCORE would
be considered to make things bold in our markdown output, making the query info
look strange.

Example https://codeql.github.com/codeql-query-help/python/py-slots-in-old-style-class/

python/ql/src/Classes/WrongNumberArgumentsInClassInstantiation.ql

@@ -1,6 +1,6 @@
 /**
  * @name Wrong number of arguments in a class instantiation
- * @description Using too many or too few arguments in a call to the __init__
+ * @description Using too many or too few arguments in a call to the `__init__`
  *              method of a class will result in a TypeError at runtime.
  * @kind problem
  * @tags reliability