quickstart: Simplify generated conf.py (common items)

[tk0miya]

Feature or Bugfix

• Feature

Purpose

• refs: The 'conf.py' generated by 'sphinx-quickstart' has too much noise #4256
• This removes need_sphinx and pygments_style

[codecov]

Codecov Report

Merging #5700 into master will increase coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #5700      +/-   ##
==========================================
+ Coverage   83.24%   83.27%   +0.03%     
==========================================
  Files         295      293       -2     
  Lines       39359    39322      -37     
  Branches     5870     5867       -3     
==========================================
- Hits        32763    32744      -19     
+ Misses       5232     5217      -15     
+ Partials     1364     1361       -3

Impacted Files	Coverage Δ
sphinx/__init__.py
sphinx/make_mode.py

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[tk0miya]

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