Enable more revive linter rules (#30608)

Noteable additions:

- `redefines-builtin-id` forbid variable names that shadow go builtins
- `empty-lines` remove unnecessary empty lines that `gofumpt` does not
remove for some reason
- `superfluous-else` eliminate more superfluous `else` branches

Rules are also sorted alphabetically and I cleaned up various parts of
`.golangci.yml`.

services/repository/adopt.go

@@ -357,7 +357,6 @@ func ListUnadoptedRepositories(ctx context.Context, query string, opts *db.ListO
 				return err
 			}
 			repoNamesToCheck = repoNamesToCheck[:0]
-
 		}
 		return filepath.SkipDir
 	}); err != nil {