Reset sync_known_lib_num when closing a connection - 2.0.x

[heifner]

Change Description

• Reset sync_known_lib_num on closing connection to optimize syncing
• When closing connection a connection we should no longer consider its view of LIB since we are no longer connected to that peer. This PR updates sync_known_lib_num with highest of known peers when a connection is closed.
• Fixed some cases where net_plugin kept trying to re-connect on fatal conditions (like chain is a differ chain (chain_id))

Change Type

Select ONE:

• Documentation

• Stability bug fix

• Other

• Other - special case

Testing Changes

Select ANY that apply:

• New Tests

• Existing Tests

• Test Framework

• CI System

• Other

Consensus Changes

• Consensus Changes

API Changes

• API Changes

Documentation Additions

• Documentation Additions

[heifner]

#10645