Warn users about limited GA4 data retention time on the settings form with link to the official documentation

Problem/Motivation

According to https://support.google.com/analytics/answer/7667196?hl=en, you cannot query visits more than 14 months old as they are deleted by Google. Mention this text on the settings form where you set the date range.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes