feat: #2652272 Review (and in most cases remove) use of target="_blank" attribute outside the installer or update.php

With the first commit we remove all occurrences of the target="_blank" in all files, and then, step by step, we will make a decision on what to keep and what to revert.

This way should me much more convenient because:

• We will have an actual dynamic list of changes.
• Each changed line will provide an easy way to look on the code around it to understand the context.
• We will be able to comment and discuss each case in a separate thread to make the final decision.

Closes #2652272