Frontend items in Tiltfile and k8s when frontend is no

[abosio]

Even when n is chosen for frontend during scaf run:

• In the Tiltfile, there are docker_build, syncback and k8s_resource items referring to "frontend"
• k8s/base/react.yaml is created and a reference to it is in k8s/base/kustomization.yaml

This causes errors during tilt up:

-- syncback extension checking for local rsync --
local: "/Users/[username]/Library/Application Support/tilt-dev/tilt_modules/github.com/tilt-dev/tilt-extensions/syncback/verify_rsync.sh" 3.0.0
 → [no output]
Traceback (most recent call last):
  /Users/[username]/Documents/[project_slug]/Tiltfile:21:13: in <toplevel>
Error in docker_build: error reading dockerfile: open /Users/[username]/Documents/[project_slug]/frontend/Dockerfile: no such file or directory