The [cache]/expiration_time currently caches items for the default
of 600s and is not configurable via the charm. This change adds a
dogpile-cache-expiration config option that will default to 600s
so as not to cause any behavior changes by default.
Closes-Bug: #1899117
Change-Id: I639b2b77d5db69744897b6798613a797d05fe23b
Co-authored-by: Chris MacNaughton <chris.macnaughton@canonical.com>
152e5b6cfe