Copy variant button is enabled for a created experiment

**This bug has appeared after the removal of extJS.

Steps to reproduce:

1. Go to the HAP channel

2. Select a component

3. Copy the variant

4. Select "Dutch" segment

5. Go to the Experiments tab

6. Select a goal

7. Save

8. Go to the "Properties" tab

Expected result:

The Copy variant button is disabled (as the rest of the buttons)

Actual result:

The buttons are enabled