Remove redundant binary conversion calculations in binary_and

[chaw-thiri]

Describe your change

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
• Documentation change?

The function converts both inputs to binary strings and calculates their lengths, but the resulting max_len is immediately overwritten using bit_length(). Remove these unnecessary calculations while preserving the existing behaviour.

Checklist

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• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
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