Fix missing XmppClient m_certStatus and m_PresenceUpdate member initialization following rP21901 and rP22855.

This might explain unexpected TLS certificate error strings upon failed TLS handshake, refs #4705.
Might or might not fix a conditional valgrind conditional jump depending on uninitialized value error reported in P170 for the XmppClient constructor (inconsistent test results).

Differential Revision: https://code.wildfiregames.com/D2278
Tested on: clang 8.0.1, gcc 9.1.0, Jenkins