In the requirement issue screen, within the Test Coverage, the available actions must be reviewed

Currently, in the story/requirement issue screen, there is a "+" action button that is somehow misleading and hidden. Also, the word "new in the buttons "Create new ..." is redundant and shall be removed.

Thus, we must do three things:

1. In the requirement issue screen, the "+" icon should be removed

2. Add a button, on the right side of the "Create new Test",  with the text "Link Test(s)")

3. Change the labels of the buttons "Create new Test" and "Create new Sub Test Execution" to "Create Test" and "Create Sub Test Execution" respectively.

In the end we should have something similar to: