Reorganize Media Gallery stores configuration UI

[sivaschenko]

Steps to reproduce (*)

1. Login to Admin Panel
2. Go to Stores -> Configuration -> Advanced -> System

Expected result (*)

0. The changes should be applied to the UI only, the values or configuration path should not be affected
1. Section label is changed from Enhanced Media Gallery to Media Gallery
2. Select label is changed from Enable to Enable Old Media Gallery
3. Select option values should be reversed
4. Corresponding MFTF action groups should be corrected
   

[m2-assistant]

Hi @sivaschenko. Thank you for your report.
To help us process this issue please make sure that you provided sufficient information.

Please, add a comment to assign the issue: @magento I am working on this

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[konarshankar07]

@magento I'm working on this