Adjust go integration tests to run on Windows

Follow-up on https://github.com/elastic/beats/issues/42920.

Following beats can't run go integration tests on Windows due to `no matching manifest for windows(10.0.20348)/amd64 in the manifest list entries:`

- filebeat: https://buildkite.com/elastic/filebeat/builds/17746#0196f7e4-aaf1-4b85-ba34-e3feb1162fa6
- libbeat: https://buildkite.com/elastic/beats-libbeat/builds/15672#0196f7e5-7c51-4783-be1c-39797824d54a
- metricbeat: https://buildkite.com/elastic/beats-metricbeat/builds/18488#0196f7ef-0703-4604-b2dc-cc91e3a6470d
- x-pack/metricbeat: https://buildkite.com/elastic/beats-xpack-metricbeat/builds/16323#0196f7e8-c3ef-4bec-a46b-07351933c266
- x-pack/heartbeat: https://buildkite.com/elastic/beats-xpack-heartbeat/builds/13702#0196f7e1-f9ad-456f-9c48-da8255578969
- x-pack/libbeat: https://buildkite.com/elastic/beats-xpack-libbeat/builds/14700
The problem is related to busybox which is built for linux containers, not the Windows ones.

And x-pack/filebeat failing with `image operating system "linux" cannot be used on this platform: operating system is not supported`: https://buildkite.com/elastic/beats-xpack-filebeat/builds/15355#0196f7ea-16d7-418f-8f88-1935a12cc5fc