(PUP-1471) Remove warning message about pausing Windows agent service

Puppet agent on windows now uses a win32-service gem which is 0.8.4 or
greater[1,2]. The warning message and inline comments are no longer
required now that the upstream bug was fixed[3].

[1] https://github.com/puppetlabs/puppet/commit/5a5e685bf835fb459d036d31f0078668f5802331
[2] https://github.com/puppetlabs/puppet/commit/784c3d17c4d3e666701559c529e46465e5dc417e
[3] https://github.com/djberg96/win32-service/commit/38eba9f1edee41c9fb1d89fc3dea11da0768baf9
Merge branch 'pr/2859'

* pr/2859:
  (PUP-1471) Remove warning message about pausing Windows agent service