Summary: In some edge cases during capacity reservation in GCP, there is a conflict during the capacity reservation creation since the reservation exists already. This diff ensures that we create the capacity reservation only if it doesn't exist. This diff also increases the garbage collection interval of used capacity reservations in GCP to 60 minutes to avoid immediate deletions.

Test Plan: Tested by aborting task after the reservation is created

Reviewers: #yba-api-review!, yshchetinin

Reviewed By: yshchetinin

Subscribers: yugaware

Differential Revision: https://phorge.dev.yugabyte.com/D55409