Save time of last GC in XAPI #525
Description
Somehow related to #524
What do you think of storing the last timestamp of when a GC was triggered on a specific SR? (like a new field in XAPI or just a record in other_config).
This might be helpful to track discrepancies between a chain that have to be coalesce and last time it was done (and likely detects SR issues before it's too late!)