[release/8.0] Bump to macos-12 build image

[akoeplinger]

AzDO will remove macos-11 in about two weeks: https://learn.microsoft.com/en-us/azure/devops/pipelines/agents/hosted?view=azure-devops&tabs=yaml#recent-updates

Essentially backports #53145

[akoeplinger]

Infrastructure change without which we can't build, adding tell-mode label.

[wtgodbe]

Thanks!

[wtgodbe]

Will merge this when the branches open up again

[akoeplinger]

/backport to release/6.0

[github-actions]

Started backporting to release/6.0: https://github.com/dotnet/aspnetcore/actions/runs/9551579425

[akoeplinger]

Failures here also happened after retry:

[xUnit.net 00:33:24.79]     Microsoft.AspNetCore.Components.E2ETest.Tests.WebAssemblyPrerenderedTest.CanPrerenderAndAddHeadOutletRootComponent [FAIL]
  Failed Microsoft.AspNetCore.Components.E2ETest.Tests.WebAssemblyPrerenderedTest.CanPrerenderAndAddHeadOutletRootComponent [16 ms]
  Error Message:
   System.IO.DirectoryNotFoundException : Test is configured to use trimmed outputs, but trimmed outputs were not found in /home/vsts/work/1/s/src/Components/test/E2ETest/bin/Release/net8.0/trimmed-or-threading/Wasm.Prerendered.Server.
  Stack Trace:
     at Microsoft.AspNetCore.Components.E2ETest.Tests.WebAssemblyPrerenderedTest.GetPublishedContentRoot(Assembly assembly) in /home/vsts/work/1/s/src/Components/test/E2ETest/Tests/WebAssemblyPrerenderedTest.cs:line 63
   at Microsoft.AspNetCore.Components.E2ETest.Infrastructure.ServerFixtures.AspNetSiteServerFixture.CreateWebHost() in /home/vsts/work/1/s/src/Components/test/E2ETest/Infrastructure/ServerFixtures/AspNetSiteServerFixture.cs:line 35
   at Microsoft.AspNetCore.Components.E2ETest.Infrastructure.ServerFixtures.WebHostServerFixture.StartAndGetRootUri() in /home/vsts/work/1/s/src/Components/test/E2ETest/Infrastructure/ServerFixtures/WebHostServerFixture.cs:line 16
   at Microsoft.AspNetCore.Components.E2ETest.Infrastructure.ServerFixtures.ServerFixture.<.ctor>b__4_0() in /home/vsts/work/1/s/src/Components/test/E2ETest/Infrastructure/ServerFixtures/ServerFixture.cs:line 22
   at System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
--- End of stack trace from previous location ---
   at System.Lazy`1.CreateValue()
   at Microsoft.AspNetCore.Components.E2ETest.Infrastructure.ServerTestBase`1.Navigate(String relativeUrl, Boolean noReload) in /home/vsts/work/1/s/src/Components/test/E2ETest/Infrastructure/ServerTestBase.cs:line 31
   at Microsoft.AspNetCore.Components.E2ETest.Tests.WebAssemblyPrerenderedTest.CanPrerenderAndAddHeadOutletRootComponent() in /home/vsts/work/1/s/src/Components/test/E2ETest/Tests/WebAssemblyPrerenderedTest.cs:line 38
   at InvokeStub_WebAssemblyPrerenderedTest.CanPrerenderAndAddHeadOutletRootComponent(Object, Object, IntPtr*)
   at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)

[wtgodbe]

Failure is unrelated