Move to 1ES servicing pools in release/latest

[jonfortescue]

We're required to move all servicing branches to the new 1ES servicing pools by September 30. This accomplishes that for release/latest.

Tracking issue: https://github.com/dotnet/core-eng/issues/14276

[MihaZupan]

We're not actively producing builds from release* branches, perhaps this should go into main instead?

[jonfortescue]

@MihaZupan I show a build from this branch on Sep 2 – is that a one-off? We'll be shutting down these pools soon so if there are any future builds from release* branches, they will fail without a change.

If you're sure that there won't be any builds, though, then yes; this can be closed and we'll make the switch to the R&D pools in main.

[MihaZupan]

There would only be a new build on that branch if we do a servicing release of an existing preview, which is rare. If we do, we can cherry-pick the pool update there.
We will merge main into release/latest within the next few weeks.

[jonfortescue]

To be clear, the pools for main and the release* branches are different. We would use the R&D pools in main and the servicing pools in the release* branches, so a pure cherry-pick from main will be inadequate.

[MihaZupan]

Oh okay, in that case doing it just in release makes sense, thanks for the explanation

[jonfortescue]

@MihaZupan any chance we can get this merged in?

[MihaZupan]

@jonfortescue Is the timeline known for when all branches (including non-servicing) will be moved onto the new pools?

[jonfortescue]

@MihaZupan best I can give you is "as soon as possible." We're working every day on moving all active servicing branches over first but we have ~80 repos we're working in, so it's going to take some time.