[release/9.0] Update WebAssembly Helix image versions (#126527)

> [!NOTE]
> This PR was AI/Copilot-generated.

Update the release/9.0 WASI and Browser WebAssembly Helix queue image
references to the published Ubuntu 26.04 WebAssembly image.

- `libraries/helix-queues-setup.yml`: move WASI, Browser WASM, and
Browser WASM Firefox to `ubuntu-26.04-helix-webassembly-amd64`
- `coreclr/templates/helix-queues-setup.yml`: move Browser WASM to the
26.04 amd64 image while preserving the existing host queue pattern on
this branch
- exact tag validated in
`image-info.dotnet-dotnet-buildtools-prereqs-docker-main.json`

Backport of #126524. Ref #125690, #126122

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: richlander

docs/workflow/building/coreclr/cross-building.md

@@ -155,7 +155,7 @@ docker run --rm \
   -v <RUNTIME_REPO_PATH>:/runtime \
   -w /runtime \
   -e ROOTFS_DIR=/crossrootfs/arm64 \
-  mcr.microsoft.com/dotnet-buildtools/prereqs:cbl-mariner-2.0-cross-arm64 \
+  mcr.microsoft.com/dotnet-buildtools/prereqs:azurelinux-3.0-net9.0-cross-arm64 \
   ./build.sh --subset clr --cross --arch arm64
 ```
 

eng/pipelines/coreclr/templates/helix-queues-setup.yml

@@ -50,7 +50,7 @@ jobs:
 
     # Browser wasm
     - ${{ if eq(parameters.platform, 'browser_wasm') }}:
-      - (Ubuntu.2204.Amd64)Ubuntu.2204.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-22.04-helix-webassembly
+      - (Ubuntu.2604.Amd64.Open)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-26.04-helix-webassembly-amd64
 
     # iOS devices
     - ${{ if in(parameters.platform, 'ios_arm64') }}:

eng/pipelines/libraries/helix-queues-setup.yml

@@ -58,8 +58,8 @@ jobs:
         # CoreCLR path
           - ${{ if and(eq(parameters.jobParameters.isExtraPlatformsBuild, true), ne(parameters.jobParameters.testScope, 'outerloop'))}}:
             # extra-platforms CoreCLR (inner loop only)
+            - AzureLinux.3.Amd64.Open
             - (Debian.12.Amd64.Open)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:debian-12-helix-amd64
-            - (Mariner.2.0.Amd64.Open)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:cbl-mariner-2.0-helix-amd64
 
           - ${{ if eq(parameters.jobParameters.testScope, 'outerloop') }}:
               # outerloop only CoreCLR
@@ -68,7 +68,7 @@ jobs:
           - ${{ if or(ne(parameters.jobParameters.isExtraPlatformsBuild, true), eq(parameters.jobParameters.includeAllPlatforms, true))}}:
               # inner and outer loop CoreCLR (general set)
               - Ubuntu.2204.Amd64.Open
-              - (AzureLinux.3.0.Amd64.Open)AzureLinux.3.Amd64.open@mcr.microsoft.com/dotnet-buildtools/prereqs:azurelinux-3.0-helix-amd64
+              - (AzureLinux.3.0.Amd64.Open)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:azurelinux-3.0-helix-amd64
               - (Centos.10.Amd64.Open)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:centos-stream-10-helix-amd64
 
     # OSX arm64
@@ -152,15 +152,15 @@ jobs:
 
     # WASI
     - ${{ if eq(parameters.platform, 'wasi_wasm') }}:
-      - (Ubuntu.2204.Amd64)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-22.04-helix-webassembly
+      - (Ubuntu.2604.Amd64.Open)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-26.04-helix-webassembly-amd64
 
     # Browser WebAssembly
     - ${{ if eq(parameters.platform, 'browser_wasm') }}:
-      - (Ubuntu.2204.Amd64)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-22.04-helix-webassembly
+      - (Ubuntu.2604.Amd64.Open)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-26.04-helix-webassembly-amd64
 
     # Browser WebAssembly Firefox
     - ${{ if eq(parameters.platform, 'browser_wasm_firefox') }}:
-      - (Ubuntu.2204.Amd64)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-22.04-helix-webassembly
+      - (Ubuntu.2604.Amd64.Open)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-26.04-helix-webassembly-amd64
 
     # Browser WebAssembly windows
     - ${{ if in(parameters.platform, 'browser_wasm_win', 'wasi_wasm_win') }}: