Avoid checkpoint-sync when we have recent state in the DB

[MegaRedHand]

We currently always checkpoint sync when the --checkpoint-sync-url flag is used. We should instead first check that we don't have a recent (i.e. within the weak-subjectivity period) state in the DB.

[guha-rahul]

Can i pick this up? @MegaRedHand

[pablodeymo]

yes @guha-rahul