Create integration test for renaming Windows system metric

The logic for deriving the default name for Windows metrics differs from Unix. Rather than using a `_` to separate, on Windows, the agent uses ` ` to separate. For example, instead of `cpu_time_active`, for the CPU plugin, the agent would hypothetically decorate the metric as `cpu time_active`. A bug was identified where we weren't properly renaming the metric when the prefix is omitted in the rename configuration, e.g.: `"rename": "time_active"` on Linux. The integration test that checks this on Linux is failing in our staging repo. There is nothing that would have caught this for Windows, as of right now. We need to add an integration test for that edge case.

Start by locating the existing Linux integration test for renaming a metric when the prefix is omitted, then find its rename configuration and Windows-specific metric setup. Add the corresponding Windows edge-case coverage for a rename such as "time_active"; done means the test verifies the expected Windows metric name using a space separator.

Written by the indexing model from the issue text.