Behavior change: Ticket cleanup mechanism

[yfei1]

Goal of this issue:
Opened this issue to track if there is any feedback against this behavior change.

Background:
Open Match has a ticket auto-expiring mechanism since v0.4.0. However, this expiration logic will introduce some memory leak in Redis so starting from v0.10.0, we will remove the ticket auto-expiring logic from our statestore implementation in googleforgames/open-match#1146. After this change, users are now responsible for deleting any unused/invalid tickets that have created in Open Match.

TODOs:
Document this behavior change in v0.10 release and the ticket cleanup mechanism in Open Match

[thevilledev]

Good choice. Currently in v0.9.0 the Redis expiration time is a burdensome thing to configure, and it affects all tickets in the system. Removing this implicit expiration and providing the ticket creation times with googleforgames/open-match#1162 in the Ticket proto is a much more flexible approach.