[cleanup] cleanup scripts/noreferences.py
[cleanup] cleanup scripts/noreferences.py

- remove preleading "u" from strings
- use single quotes for string literals and double quotes
  **only** if they consist of single quotes within them
- use str.format(...) instead of modulo for type specifier
  arguments

Change-Id: I05e8b69b7ca0ce522401179a2f64aeeb3170ca1d

wikimedia/pywikibot-core,PersianWikipedia/pywikibot-core,wikimedia/pywikibot-core