[rptest] TxWorkload in Python (for PESDLC-1490)

[clee]

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(in-progress) port of TxWorkload from Java to Python.

Backports Required

• [x] none - not a bug fix
• [ ] none - this is a backport
• [ ] none - issue does not exist in previous branches
• [ ] none - papercut/not impactful enough to backport
• [ ] v24.2.x
• [ ] v24.1.x
• [ ] v23.3.x

Release Notes

• none