[wasm] Use the docker images with floating tags (#85388)

We switched it temporarily to specific version around 3.1.34 bump,
so get back to floating tags again

Author: radekdoulik

eng/pipelines/common/templates/pipeline-with-resources.yml

@@ -75,10 +75,10 @@ resources:
       image: mcr.microsoft.com/dotnet-buildtools/prereqs:centos-stream8
 
     - container: browser_wasm
-      image: mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-18.04-webassembly-net8-20230327150025-4404b5c
+      image: mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-18.04-webassembly-net8
 
     - container: wasi_wasm
-      image: mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-20.04-webassembly-net8-20230327150037-4404b5c
+      image: mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-20.04-webassembly-net8
 
     - container: freebsd_x64
       image: mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-18.04-cross-freebsd-12

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

@@ -197,6 +197,6 @@ jobs:
 
     # Browser WebAssembly windows
     - ${{ if in(parameters.platform, 'browser_wasm_win', 'wasi_wasm_win') }}:
-      - (Windows.Amd64.Server2022.Open)windows.amd64.server2022.open@mcr.microsoft.com/dotnet-buildtools/prereqs:windowsservercore-ltsc2022-helix-webassembly-net8-20230327150108-4404b5c
+      - (Windows.Amd64.Server2022.Open)windows.amd64.server2022.open@mcr.microsoft.com/dotnet-buildtools/prereqs:windowsservercore-ltsc2022-helix-webassembly-net8
 
     ${{ insert }}: ${{ parameters.jobParameters }}