Update Dockerfile.windows with changes missed in #607. (#640)
Update Dockerfile.windows with changes missed in #607. (#640)

#607 included changes that altered build flags for gradle because of an [upstream change](https://github.com/open-telemetry/opentelemetry-java-contrib/pull/274) -- unclear whether this was necessary for the purpose of the PR or not (to add a metrics receiver for Jetty). These changes were only made for the Linux build, but not Windows, breaking the Windows builds. 

See https://github.com/GoogleCloudPlatform/ops-agent/pull/607/files#r880772695
GoogleCloudPlatform/ops-agent,GoogleCloudPlatform/ops-agent