Adjust description of several form elements

Problem/Motivation

Some of the descriptions of the form elements are still quite misleading or incorrect, e.g. for enabling identifying users in posthog js:

Enables identifying users client-side. This means, that all client-side events will become identified events. See Anonymous vs identified events and Events for more information. Make sure "Enhanced User identification" is setup as required.

→ that is incorrect. Anonymous users always fire anonymous events.

Steps to reproduce

Proposed resolution

Fix the descriptions.

Remaining tasks

User interface changes

API changes

Data model changes