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`.

routers/api/v1/repo/repo.go

@@ -1084,7 +1084,6 @@ func updateMirror(ctx *context.APIContext, opts api.EditRepoOption) error {
 
 	// update MirrorInterval
 	if opts.MirrorInterval != nil {
-
 		// MirrorInterval should be a duration
 		interval, err := time.ParseDuration(*opts.MirrorInterval)
 		if err != nil {