Remove attachment points setting from template library structures since they're not used anymore

[d-mrzv]

Background
Each structure template in Template Library has attachment points setting (one atom and one bond can be set as attachment points).

Before #1954 was implemented these points were used when structures from template library were attached to structured on canvas. Now since user sees the structure at the cursor they can choose any atom or bond.
https://user-images.githubusercontent.com/124911723/224988013-4704d2dc-d086-4147-bc0b-e70f9e847f34.mov

Solution
Remove attachment points setting from structures from template library.