Improve selfrepair summary download

[ghost]

Description

Implement a faster download of the beacon summaries during self-repair

Fixes #385

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Simulate a delay in the P2P messages (for example 200ms), and run one node. After 1/2 cycle of self-repair, run a 2nd node, the self-repair should be performed in few seconds.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules