Description

Removes obsolete fuzzing code and update readme.md about how fuzzer works.

Fixes#467

Type of Change

• Minor bug fix (non-breaking small changes)

Checklist (remove irrelevant options):

• The change followed the style guidelines of the UTBot project
• Self-review of the code is passed
• The change contains enough commentaries, particularly in hard-to-understand areas
• New documentation is provided or existed one is altered
• No new warnings
• All tests pass locally with my changes