[BB-5077] fix: End of trial email sent to paying customer

Description

This PR is fix for a bug identified in OCIM application, where a paying client would get an end of trial reminder email after they launched a new appserver

Supporting information

BB-5077

Testing instructions

1. Register a new trial instance in OCIM
2. Once the first app server is ready, delete the corresponding entry created in Subscribers table from the Django admin page
3. Launch a new appserver from console
4. After the new appserver is up and ready, check that there should be no new entry in the Subscribers table

Deadline

"None"