[Source] source is not removed and audio item is not removed from mixer list

[wangshaohui]

Platform
Operating system and version: Win10 x64
OBS Studio version: OBS.25.0.8 x64
This issue can be reproduced 100%.

Expected Behavior

1. after removing all sources, related audio items should be removed from audio mixer list;
2. after removing all sources, when to add new source, there should be no existed source;

Current Behavior

1. In step (5), audio item is not removed from mixer list;
2. In step (6), there is existed source.

Steps to Reproduce

1. add scene-1 and scene-2;
2. in scene-1, add a group source and a media source, drag media source into group;
3. in scene-2, add existed group source, add scene source with scene-1;
4. in scene-2, drag media source out of group source;
5. in scene-2, remove all sources, check audio mixer list : item of media is not removed (BUG-1);
6. in scene-1, remove all sources, try to add new media source : there still exist media source even all sources are removed (BUG-2);

Additional information
In step 5 and 6, the two bugs seem caused by disordered reference count of actice_ref and obs_source_t.