Tweak uWSGI metricset fields

[iahmedov]

As suggested by @ruflin here #6006,

• field names should be tweaked [Metricbeat] new uWSGI module #6006 (comment)
• data generation in metricset examples should be autogenerated [Metricbeat] new uWSGI module #6006 (comment)

If any other suggestions please include here.

(Can someone assign it to me?)

[jlind23]

Backlog grooming: Closing it for now until further activity, can still be reopened if needed.