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/wiki.go

@@ -478,7 +478,6 @@ func findEntryForFile(commit *git.Commit, target string) (*git.TreeEntry, error)
 func findWikiRepoCommit(ctx *context.APIContext) (*git.Repository, *git.Commit) {
 	wikiRepo, err := gitrepo.OpenWikiRepository(ctx, ctx.Repo.Repository)
 	if err != nil {
-
 		if git.IsErrNotExist(err) || err.Error() == "no such file or directory" {
 			ctx.NotFound(err)
 		} else {