Fix DAG-level permissions disappearance on DAG sync

[TruthIsNear]

Closes: #32839

Adds back the code that was removed in #30340

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[uranusjr]

How does this affect the issue #30340 is supposed to solve?

Also cc @huymq1710

[TruthIsNear]

How does this affect the issue #30340 is supposed to solve?

Seems like this PR does introduce that issue back

[potiuk]

I rebased it and marked is as 2.7.0. Indeed the #30340 removed syncing where it was still needed and reverting the change seems to solve the problem.

I think this is a blocker for people who use it and want to migrate so having it fixed in 2.7.0 would be great.

[potiuk]

I am not sure however if that one is just a band-aid.

Can someone - who knows how the logic of dag permissions syncing was supposed to work? I would like to understand it, because it seems that almost no-one knows how it should work and it is certainly not documented. A slimple logical description of what should happen here might be very useful. I am hppy to take a closer look and try to do it properly. but I need some guidance. I've never touched this part of code and it's a bit of mystery for me on how it should work - but I ema willing to learn @kaxil @jedcunningham @uranusjr. Maybe a birds eye view on that one ??

I think we dropped a ball on that one for 2.6.2 and mostly because we had too little expert knowledge there.

[potiuk]

I thin @SamWheating #33632 solution is a better solution. Closing this one in favour of it.

[potiuk]

Closing in favour of just merged #33632