As more and more options can be set for creating the repository, I don't
think we should put all of them into the creation web page which will
make things look complicated and confusing.
And I think we need some rules about how to decide which should/should
not be put in creating a repository page. One rule I can imagine is if
this option can be changed later and it's not a MUST on the creation,
then it can be removed on the page. So I found trust model is the first
one.
This PR removed the trust model selections on creating a repository web
page and kept others as before.
This is also a preparation for #23894 which will add a choice about SHA1
or SHA256 that cannot be changed once the repository created.
c08d263a19