EPIC: Integration tests running on windows

**Why?** We have recently started to run backend tests on windows images ([PR](https://github.com/grafana/grafana/pull/66438)) This leads to a lot of tests failing as they do not seem to work on windows ([Example drone run](https://drone.grafana.net/grafana/grafana/111456/6/4)) This EPIC is used to track fixing those tests across different squads to make sure the tests are running properly in windows builds. Feel free to create sub-issues linked to this epic and track them in your project boards. Currently the PR above will mark the tests optional, but we hope to get them green soon and start making them required. **How to know which tests are failing?** Take a look at the example drone run linked above or run the tests locally. If you're already working on a PR, you can also take the Drone build for that PR and then *promote* it with the target "test-windows" to run the windows tests in their own pipeline. <img width="932" alt="Screenshot 2023-05-10 at 16 52 39" src="https://github.com/grafana/grafana/assets/3782/e8142445-d3bd-4e48-9175-2daffc4cc024"> **How to run the tests locally?** Seems only possible if you have a windows machine you can use. If you find another way, add it here. **Tracking of test areas by squad:** ```[tasklist] ### Backend Platform - [ ] pkg/util - [ ] pkg/api/dashboard_test.go - [ ] pkg/api/frontend_logging_test.go - [ ] pkg/build/cmd - [ ] pkg/build/fsutil - [ ] pkg/infra/fs - [ ] pkg/infra/httpclient/httpclientprovider/http_logger_middleware_test - [ ] pkg/services/notifications - [ ] pkg/services/rendering - [ ] pkg/services/sqlstore/migrations - [ ] pkg/services/sqlstore/migrations/accesscontrol/test ``` ```[tasklist] ### Observability Metrics - [x] grafana/pkg/expr ``` ```[tasklist] ### Grafana SaaS - [x] pkg/infra/proxy ``` ```[tasklist] ### Plugins Platform - [ ] pkg/plugins/manager/dashboards - [ ] pkg/plugins/manager/loader - [ ] pkg/plugins/manager/loader/finder - [ ] pkg/plugins/manager/signature - [ ] pkg/plugins/manager/sources …