Impose blob size limit in the manager before calling DALC SubmitBlocks

[gupadhyaya]

Currently all blocks from the pendingBlocks queue is pulled to call SubmitBlocks using DALC, which may lead to DA submission failures if the total blob size exceeds the limit. May be DALC interface provides a method to get the blob size limit which can then be used by the caller (manager).

[nashqueue]

cc @tzdybal