Gateway client deadline config

[suddendust]

Description

These changes are in context of: https://github.com/hypertrace/hypertrace-core-graphql/issues/69. Currently, we hardcode the deadline as 10s. Now, GATEWAY_SERVICE_DEADLINE is read from application.conf

Testing

Test and deployed the application locally.

Checklist:

• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] Any dependent changes have been merged and published in downstream modules

[suddendust]

you may have to update submodules once the dependent PR merge.

Done @kotharironak thanks