Remove download of custom metrics template

[kalantar]

Iter8 commands have a number of options that are a URL. Iter8 downloads the target and uses the result as input or configuration. It would be better if the configuration were provided directly instead of downloaded (which requires a writable container). This would improve container security.

One place where this is the case is the configuration of the custommetrics task. One identifies a template using a URL. This could be replaced by in-lining the configuration instead.