R1:0f02d79ffa9d

Remove nonfunctional Mercurial "bundle2" capability filtering from SSH pathway

Summary:
Ref T13036. This code attempts to filter the "capabilities" message to remove "bundle2", but I think this has never worked.

Specifically, the //write// pathway is hooked, and "write" here means "client is writing a message to the server". However, the "capabilities" frame is part of the response, not part of the request. Thus, this code never fires, at least on recent versions of Mercurial.

Since I plan to support…