Redundant attester duty fetch on node's first startup epoch

[olegshmuelov]

Describe the bug
When a node is started during the first half of an epoch, it redundantly fetches attester duties for the next epoch in slots 16 and 17. This causes unnecessary duty fetches earlier than expected.
could be the same is happening for sync committee duties.

To Reproduce
Start the node on slot position 1-15.
Duties for the next will be fetched on on slot position 16 and slot position 17

Expected behavior
Duties should be fetched only once on slot position #17