Removed FTP proxy settings from default proxy

[martingrossmann]

Description

Since Firefox 90 the FTP proxy settings are no longer supported: https://blog.mozilla.org/addons/2021/04/15/built-in-ftp-implementation-to-be-removed-in-firefox-90/.

There is also a note from Selenoid developers: aerokube/selenoid-container-tests#11

Therefor WebDriverProxyUtils shouldn't set it per default, but only proxy for HTTP or HTTPS.

Fixes # (issue)

Type of change

Please delete options that are not relevant.

• 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)
• This change requires a documentation update

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 made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules