fix: remove dead code from utils and adaptive_crawler

[RajanChavada]

Summary

Please include a summary of the change and/or which issues are fixed.

Removes unreachable and abandoned code that accumulated over time. No behaviour change.

List of files changed and why

• crawl4ai/adaptive_crawler copy.py: editor artifact committed by mistake; byte-for-byte duplicate of
  adaptive_crawler.py, not imported anywhere. Deleted.
• crawl4ai/utils.py: two dead normalize_url variants removed:
  • The first normalize_url definition was silently shadowed by the extended definition ~20 lines below it.
    Python last-write wins, so it was never callable.
  • normalize_url_tmp had zero callers outside utils.py itself and reimplemented what urllib.parse.urljoin already
    does correctly.

How Has This Been Tested?

Existing test suite passes (pytest). No callers of removed code exist -> confirmed by grep across the full codebase before removal. extract_xml_data_legacy (also "legacy"-named) was left in place because tests/regression/test_reg_utils.py uses it.

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
• I have added/updated unit tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[RajanChavada]

Requesting a review on this PR (tagging @unclecode) as the lead maintainer :)

[ntohidi]

Reviewing the PR...

[ntohidi]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

Notes:

• Confirmed the shadowed normalize_url (first definition) was never callable due to Python's last-write-wins behavior. The canonical version with keyword args is preserved.
• Confirmed normalize_url_tmp has zero callers across the codebase.
• adaptive_crawler copy.py is not importable (space in filename) and was never referenced. Note: the PR description says "byte-for-byte duplicate" but it is actually an older, diverged snapshot missing several fields added later. The deletion is still correct -- just the justification could be more precise.

@RajanChavada Thanks for your contribution :)