Remove OS support tests from TemplateBuilderLiveTest, as people are ignoring failures

Developers don't seem to be running live tests much anymore. Prime example is [even amazon ec2 is now rusting](https://issues.apache.org/jira/browse/JCLOUDS-775)!

Part of this is likely that they fail for trivial reasons due to a somewhat obsessive test approach I introduced many years ago. Basically, we defined the "supported operating system" list in subtypes of BaseTemplateBuilderLiveTest. We once thought that we would test multiple os families, but we've never done that. In the mean time, the supported operating system part of the test is just something that breaks every 3 months when a provider adds or removes an OS version. Since there's no action we can take on that, and this drowns out real issues in the provider, let's remove it.

What we retain are more important aspects, such as properties apply, or that the default template resolves to known values. Since all our tests work off the resolved template, we do need to be aware when that changes.

https://issues.apache.org/jira/browse/JCLOUDS-778