fix(datasource): trim trailing slash in registry url (#11392)

lib/datasource/docker/index.spec.ts

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

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

lib/datasource/gitlab-tags/index.ts

lib/datasource/index.ts

...tasource/jenkins-plugins/__snapshots__/index.spec.ts.snap

lib/datasource/nuget/__snapshots__/index.spec.ts.snap

lib/datasource/pypi/__snapshots__/index.spec.ts.snap

lib/datasource/repology/__snapshots__/index.spec.ts.snap

lib/datasource/repology/index.ts

lib/datasource/rubygems/__snapshots__/index.spec.ts.snap

lib/util/url.spec.ts

lib/util/url.ts