The additional check is based on cluster being bootstrapped and the last
backup being a SST.
The change includes new function for checking the last backup was SST and unittests to verify said function as well as the main charm_check_func where the check is used and seeded file is replaced.
Closes-Bug: #2000107
Signed-off-by: Rafael Lopez <rafael.lopez@canonical.com>
Change-Id: I8e516059da5299cc0e0ce8ef0802d3a46abb1a54