Remove Thread credential sync from start of Matter commissioning flow

[jpelgrom]

Summary

After discussion with @agners, remove Thread credential syncing from the start of the Matter commissioning flow. There are 2 major reasons for this:

• it significantly slows down the flow while only being useful some of the time (initially, and on Thread network/BR changes)
• the results have limited usefulness because the API limits how much Home Assistant can influence the device data

The alternative for the user is to use the manual 'import credentials' button in the frontend (matching iOS), or access the sync option in the app settings > troubleshooting menu.

This should result in a more reliable user experience when using Matter and prevents unstable/unfinished Thread work on the core and app side 'polluting a real device'. Adding a comment in the code in case/when we revisit this in the future.

Screenshots

n/a / the Thread permission dialog will no longer show up when doing Matter commissioning

Link to pull request in Documentation repository

n/a, this behavior wasn't documented, general Thread companion app import/export documentation to be done independently

Any other notes

[agners]

As it is now, this only really would be helpful for the very first time, if the user has indeed a Home Assistant controlled OTBR, and if he was indeed triggering the flow from within the Home Assistant Android App and has no Google Thread border router yet. For all other use-cases this currently just adds lot of waiting time.

[jpelgrom]

I'd argue that there is still some value if you do not have OTBR but do have Google border routers, as this would get their dataset into Home Assistant (where you can't really use it but maybe for futureproofing?).

[agners]

I'd argue that there is still some value if you do not have OTBR but do have Google border routers, as this would get their dataset into Home Assistant (where you can't really use it but maybe for futureproofing?).

I think both direction can be useful, it is just that very few use cases are actually benefit from it. Even when there is no Thread network on a phone, importing only seems to work once (at least in my test case, see #4146).

When a user has no TBR and uses a HA OTBR, then he probably wants to import, but even that is not a 100% given, especially since the limitations on Android side means he will be stuck with that setup (and we decided for him 😅 ).

I think in the current situation, and since the sync is rather slow, it is just better to only do this manually. We can revisit an automatic mechanism later.