Lower `DEPLOY_ENV` maximum length to 8
Lower `DEPLOY_ENV` maximum length to 8

We now have an ELB unfortunately named `<env>-cf-router-system-domain`
(your're welcome), so, due to the limit of 32 characters in an ELB name,
we have to limit this variable to 8 characters.

alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf