[commtest] Fix code version for grpc client tests

Summary:
Identity service has min-version hardcoded to 270 while the test was providing 100, which caused failure due to "Unsupported version".
Changed it to 1000 to give us some time. When it fails next time we can bump it up again, unless we have better ways of setting the value.

Test Plan: The test no longer fails

Reviewers: varun, jon

Reviewed By: varun

Subscribers: ashoat, tomek, wyilio

Differential Revision: https://phab.comm.dev/D9531