[services] Remove export from the package.json scripts

Summary:
At the D4126 @ashoat made a suggestion that we don't need to export in the services package.json file for the environment variable export to the bash scripts. We can remove it from the package.json scripts section.

Linear task: ENG-1197

Test Plan: Running yarn run-backup-service-dev-mode successfully passed COMM_SERVICES_DEV_MODE=1 environment variable to the binary inside the Docker container and executed the dev-mode.

Reviewers: karol-bisztyga, palys-swm, ashoat

Reviewed By: karol-bisztyga, palys-swm, ashoat

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

Differential Revision: https://phabricator.ashoat.com/D4136