Bootstrap sync with ETH1 increase cpu

[nivBlox]

Describe the bug Once Operator with large amount of validators is syncing eth1 data from scratch, the cpu increases duo to not optimise way of syncing.

To Reproduce Steps to reproduce the behavior:

1. Clear storage (if needed)
2. Bootstrap Operator node

Expected behavior Initial sync shouldn't be so cpu consuming.

[amirylm]

We can expect the CPU to be increased, but it should be in a managed way where we control how much resources are allocated for this process.