fix: avoid modifying the original http.Request in RoundTripper

mentioned in merge request gitlab-org/duo-workflow/duo-workflow-executor!200

mentioned in merge request gitlab-zoekt-indexer!698 (merged)

mentioned in merge request gitlab-elasticsearch-indexer!762 (merged)

mentioned in merge request gitlab-com/gl-infra/platform/runway/example-service!439 (merged)

mentioned in merge request release-tools!4517 (merged)

mentioned in merge request gitlab-com/gl-infra/woodhouse!613

mentioned in merge request gitlab-org/auth/glgo!188

mentioned in merge request gitlab-org/cells/topology-service!372 (merged)

mentioned in merge request gitlab-com/gl-infra/cmbr!433 (merged)

mentioned in merge request container-registry!2564 (merged)

mentioned in merge request gitlab!208421