Room members who left are listed with the actual members

[manuroe]

From riot-android created by giomfo: element-hq/riot-android#2744

To reproduce:

• Create a private room with userA
• Invite userB
• userB joins the room, then leaves it
• when userA checks the room members list, the userB is still present NOK

[giomfo]

Note: the same sanity check must be reported here https://github.com/matrix-org/matrix-ios-sdk/blob/1fa4f1ebf964ee0a879962d8ef04a81294f6d5ae/MatrixSDK/Data/MXEventTimeline.m#L525

[giomfo]

fixed at the SDK level