[$10] Env variable to switch off weekly survey

[maxceem]

Add an env variable that would switch off sending weekly surveys for work periods. Similar like we can switch off payments https://github.com/topcoder-platform/taas-apis/blob/hotfix/send-survey-workperiods/config/default.js#L199

[maxceem]

@yoution would you like to pick this up?

[yoution]

@maxceem please assign to me

[maxceem]

@yoution paid via https://www.topcoder.com/challenges/4f814496-4e3e-4bc9-a4e6-75159944f3b8