Don't override passed in STATIC_DEV env var in startup.sh
Don't override passed in STATIC_DEV env var in startup.sh

Instead, conditionally set it to a default.

YOTOV-LIMITED/whitehall,hotvulcan/whitehall,YOTOV-LIMITED/whitehall,ggoral/whitehall,ggoral/whitehall,ggoral/whitehall,alphagov/whitehall,hotvulcan/whitehall,robinwhittleton/whitehall,askl56/whitehall,hotvulcan/whitehall,YOTOV-LIMITED/whitehall,YOTOV-LIMITED/whitehall,robinwhittleton/whitehall,askl56/whitehall,robinwhittleton/whitehall,askl56/whitehall,alphagov/whitehall,askl56/whitehall,alphagov/whitehall,alphagov/whitehall,robinwhittleton/whitehall,hotvulcan/whitehall,ggoral/whitehall