Add the jenkins command to source control so that we can update it without having to fiddle with the jenkins UI.
Add the jenkins command to source control so that we can update
it without having to fiddle with the jenkins UI.

It also allow us to move files without breaking the CI since we
won't be hard coding the locations of scripts in the jenkins UI.

matrix-org/matrix-doc,matrix-org/matrix-doc,matrix-org/matrix-doc,matrix-org/matrix-doc