[services] Blob - Delete dangling build_server.sh script

Summary:
Depends on D3970

I missed deleting this script back in D3906

Test Plan:
The blob service should still build properly

cd services
yarn run-blob-service

Reviewers: palys-swm, ashoat

Reviewed By: ashoat

Subscribers: ashoat, palys-swm, Adrian, atul, yayabosh

Differential Revision: https://phabricator.ashoat.com/D3985