Fix and refactor markdown rendering (#32522)

routers/web/repo/wiki.go

@@ -289,9 +289,8 @@ func renderViewPage(ctx *context.Context) (*git.Repository, *git.TreeEntry) {
 	}
 
 	rctx := &markup.RenderContext{
-		Ctx:         ctx,
-		ContentMode: markup.RenderContentAsWiki,
-		Metas:       ctx.Repo.Repository.ComposeDocumentMetas(ctx),
+		Ctx:   ctx,
+		Metas: ctx.Repo.Repository.ComposeWikiMetas(ctx),
 		Links: markup.Links{
 			Base: ctx.Repo.RepoLink,
 		},