refactor: artifactUpdateApproach -> skipInstalls

docs/usage/self-hosted-configuration.md

lib/config/__snapshots__/migration.spec.ts.snap

lib/config/definitions.ts

lib/config/migration.spec.ts

lib/config/migration.ts

lib/manager/npm/extract/__snapshots__/index.spec.ts.snap

lib/manager/npm/extract/index.ts

lib/manager/npm/post-update/lerna.spec.ts

lib/manager/npm/post-update/lerna.ts

lib/manager/npm/post-update/npm.spec.ts

lib/manager/npm/post-update/npm.ts

lib/manager/npm/post-update/yarn.ts

lib/manager/types.ts

...pository/extract/__snapshots__/manager-files.spec.ts.snap