Remove unsupported gates from default gate set.

[elenbaasc]

• Removed SWAP, sqrtSWAP, and CCZ from the default_gates.py
• Removed tests specifically involving these gates

[rturrado]

It may be useful tagging develop right after merging this so that, when we have to add this again in the future, we quickly localize the commits to reverse cherry-pick.

git tag just_after_removing_swap_sqrt-swap_and_ccz
git push origin just_after_removing_swap_sqrt-swap_and_ccz

But I would ask @oschusler first to see if this is a good practice or there may be better ways (this way, I suppose we can quickly dirty the list of tags).