fix: improve performance of network diagram

[bethesque]

Cap the number of pacticipants that are included in the network diagram for performance and readability reasons

PACT-1070

[bethesque]

Goodbye to some of least scalable code I have ever written 😆

[vwong]

LGTM

[bethesque]

For future reference, the way the "group" is loaded now is to start with the pacticipant in the "center", find all integrations that involve that pacticipant, identify the newly "found" pacticipants, then find all their integrations, and loop until we aren't finding any more new pacticipants (ie. we've found the end of the group). This means the number of queries required to identify the group scales linearly with the maximum number of hops between the initial pacticipant and the furthest pacticipant in the group, which performs acceptably well in my tests. We now also cap the number of pacticipants we return in the group, because the graph in the UI breaks once it hits around 200 pacticipants, so there's no point going any further.