Fix bootstrap issue

[Neylix]

Description

Fixe some error hapening on bootstrap :

• Start the tcp listener after the bootstrap to avoid connection and disconnection on the other nodes
• As now a node can send message but without starting the tcp listener, we remove the set_connected function as the node may not be connected
• Fix an error during self repair: if there is more dates to sync than CPU cores, some beacon summaries with different timestamp where aggregated together causing a crash on transaction loading

Type of change

• Bug fix (non-breaking change which fixes an issue)

Launch a node and wait half an hour to let it generate more than 30 summaries.
Create some transfer transaction
Start a second node and the should load all the transaction sorted by timestamp

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