Change settings order and fix percentage display for Fuzzing/Symbolic ratio

[alisevych]

Description

Fixes #1857
Possible improvements TBD (see #2177) and added.

Also after switch to IDEA 2022.3+ there was issue with Fuzzing/Symbolic ratio:
percentage was not displayed on UI until any change to it was made.
This PR also fixes this issue.

• When PR is ready - add the task to update User guide.

How to test

Automated tests

none

Manual tests

1st

1. Checkout this branch.
2. Run gradle runIde task.
3. Open a project in the debug IDEA.
4. Open File -> Settings -> Tools -> UnitTestBot
5. Check settings layout
6. Check Fuzzing/Symbolic percentage is displayed
7. Move the slider and check labels are changing correctly.

2nd

1. Create a new project
2. Open settings
3. Check default settings (or changed in ~/.utbot/settings.properties) are displayed.

3rd

1. Change ratio
2. Check it is saved in .idea/utbot-settings.xml

Self-check list

• I've set the proper labels for my PR (at least, for category and component).
• PR title and description are clear and intelligible.
• I've added enough comments to my code, particularly in hard-to-understand areas.
• The functionality I've repaired, changed or added is covered with automated tests.
• Manual tests have been provided optionally.
• The documentation for the functionality I've been working on is up-to-date.