This server parameter is intended to support the implementation of a consensus protocol for two phase index builds. This setting will be used by the createIndexes command or IndexBuildsCoordinator when processing a new index creation request from the client. The initial default for this server parameter should be consistent with the current two phase index build behavior where we do not consider any commit quorum before writing a commitIndexBuild oplog entry.

Additionally, we should provide a way for JS tests to check this setting, possibly though the serverStatus output.

We should also add a builder to the CI system that explicitly sets this server parameter to provide coverage for the index build commit quorum.