Separate fullnode & supernode devnet checkpoint sync into two separate jobs

[jimmygchen]

Issue Addressed

The supernode checkpoint sync test was failing to backfill, it seems like the blob count on devnet-3 may be too high for a github hosted runner to run both a supernode and a fullnode.

Separating it into a separate test to see if it passes. Devnet-3 is probably going to be removed soon but I think it's worth try this out as we may want to test supernode sync on sepolia.

[chong-he]

Maybe also need to modify the script scripts/tests/checkpoint-sync.sh? Because currently the script will start 2 nodes each (1 fullnode and 1 supernode). But after modification, there is only 1 node in each test.

I see that the supernode has completed the backfill, but the devnet-supernode CI is failing because it still has fullnode there to check (but it shouldn't as there is only 1 node after this change)