fix: Do not leave the conference soon after a conference-request.

[bgrozev]

Fixes a race condition in which the conference was stopped while a
client was in the process of joining.

[codecov]

Codecov Report

Merging #1119 (d95d74b) into master (067e575) will increase coverage by 0.01%.
The diff coverage is 60.00%.

@@             Coverage Diff              @@
##             master    #1119      +/-   ##
============================================
+ Coverage     27.86%   27.88%   +0.01%     
- Complexity      473      474       +1     
============================================
  Files           128      128              
  Lines          7783     7792       +9     
  Branches       1064     1066       +2     
============================================
+ Hits           2169     2173       +4     
- Misses         5342     5346       +4     
- Partials        272      273       +1     

Files	Coverage Δ
...otlin/org/jitsi/jicofo/xmpp/ConferenceIqHandler.kt	53.53% <100.00%> (+0.47%)	⬆️
...tsi/jicofo/conference/JitsiMeetConferenceImpl.java	44.65% <55.55%> (-0.07%)	⬇️

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[bgrozev]

Jicofo needs to leave the room when the last occupant leaves, otherwise "end conference" can not be enforced. We'll address the issue with a client reload instead