Fix getting the text before anonymizing

[shiranr]

Change Description

Fix the way we get the text for anonymization, get it from the original text and not from the anonymized one to make sure we are not overlapping with wrong text as in issue #888.

Issue reference

This PR fixes issue #888

Checklist

• [ X ] I have reviewed the contribution guidelines
• [ X ] I have signed the CLA
• [ X ] My code includes unit tests
• [ X ] All unit tests and lint checks pass locally
• [ X ] My PR contains documentation updates / additions if required

[omri374]

Looks great, thanks!