chore: remove unused functions serialize_callback_handler and deserialize_callback_handler

[anakin87]

Related Issues

These utility functions are probably a leftover.

I checked that they are not used anywhere: haystack, core-integrations, integrations page, website, tutorials, cookbook...

Some related issues (in case you are interested in history 😃): #6979 #6988 deepset-ai/haystack-core-integrations#415

Proposed Changes:

Remove these functions

How did you test it?

CI

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test:.
• I documented my code
• I ran pre-commit hooks and fixed any issue

[coveralls]

Pull Request Test Coverage Report for Build 10298900492

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.02%) to 90.167%

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Files with Coverage Reduction	New Missed Lines	%
components/generators/utils.py	1	66.67%

Totals
Change from base Build 10284638870:	0.02%
Covered Lines:	6914
Relevant Lines:	7668

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💛 - Coveralls

[davidsbatista]

LGTM - also did a double check and seems are not being used anywhere