[matrixRTCSession] Rename membership manager configuration to use the associated technical terms

[toger5]

The names already have been defined in: #4714
But it needs to be ported on top of the new MembershipManager.

Moved out of: https://github.com/element-hq/voip-internal/issues/265

[toger5]

This is merged and done!!