Builder role should allow building an installer with a previously built commit

[matoval]

The builder role currently doesn't allow the user to build an installer using an already built commit.
We should provide the option to build an installer using an existing commit.
We need this functionality to run integration tests for installers, currently integration tests can't test installers because of the total size needed. This fix would allow us to test installers because we would only need to build the installer part and not the commit.