fix: remove unused youtube params

[ReenigneArcher]

Description

Remove unused youtube params/preferences.

YouTube credentials not necessary since we don't allow any age restricted videos in the ThemerrDB.

Screenshot

Issues Fixed or Closed

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Dependency update (updates to dependencies)
• Documentation update (changes to documentation)
• Repository update (changes to repository files, e.g. .github/...)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated the in code docstring/documentation-blocks for new or existing methods/components

Branch Updates

LizardByte requires that branches be up-to-date before merging. This means that after any PR is merged, this branch
must be updated before it can be merged. You must also
Allow edits from maintainers.

• I want maintainers to keep my branch updated

[codecov]

Codecov Report

Merging #232 (a17f486) into nightly (4172903) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff            @@
##           nightly     #232   +/-   ##
========================================
  Coverage    66.55%   66.55%           
========================================
  Files           11       11           
  Lines          882      882           
========================================
  Hits           587      587           
  Misses         295      295           

Flag	Coverage Δ
Linux	66.55% <ø> (ø)
Windows	66.55% <ø> (ø)
macOS	66.55% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
Contents/Code/default_prefs.py	100.00% <ø> (ø)
Contents/Code/youtube_dl_helper.py	74.32% <ø> (ø)