test: simplify nock handling (#10170)

lib/config/presets/bitbucket-server/index.spec.ts

lib/config/presets/bitbucket/index.spec.ts

lib/config/presets/gitea/index.spec.ts

lib/config/presets/github/index.spec.ts

lib/config/presets/gitlab/index.spec.ts

lib/datasource/bitbucket-tags/index.spec.ts

lib/datasource/cdnjs/index.spec.ts

lib/datasource/clojure/index.spec.ts

lib/datasource/crate/index.spec.ts

lib/datasource/dart/index.spec.ts

lib/datasource/datasource.spec.ts

lib/datasource/docker/common.spec.ts

lib/datasource/docker/index.spec.ts

lib/datasource/galaxy-collection/index.spec.ts

lib/datasource/galaxy/index.spec.ts

lib/datasource/github-releases/index.spec.ts

lib/datasource/github-tags/index.spec.ts

lib/datasource/gitlab-tags/index.spec.ts

lib/datasource/go/index.spec.ts

lib/datasource/gradle-version/index.spec.ts