[CONTROLLER-2031] Add specific config knob for the size of AppendEntries

Relates — Tue, 2 May 2023 20:57:53 +0000

Until now the knob shard-snapshot-chunk-size was used to determine
the max size of snapshot chunks as well as AppendEntries messages.
These objects however play roles in two different processes:

snapshot capture and installation
journal replication

Adding a separate config knob for the max size of AppendEntries messages will allow the user to tweak the two systems independently and more precisely.

OpenDaylight JIRA

[CONTROLLER-2031] Add specific config knob for the size of AppendEntries