Disabling Microsoft.AspNetCore.Routing.Microbenchmarks

## Failing Test(s)

- Microsoft.AspNetCore.Routing.Microbenchmarks

This has failed 3 times in the last week and is currently the top cause of build failures. I don't think we have a way to quarantine microbenchmarks like we do for regular tests, so I'm marking it as skipped. The owning team can unskip it once a fix is applied.

Note that there are many other microbenchmark projects in this repo that have not caused any build failures, so getting 3 failures from the routing ones suggests the issue is somehow specific to this microbenchmark and not to the infrastructure in general.

## Error Message

```text
(NETCORE_ENGINEERING_TELEMETRY=Build) The command "dotnet D:\a\_work\1\s\artifacts\bin\Microsoft.AspNetCore.Routing.Microbenchmarks\Release\net10.0\Microsoft.AspNetCore.Routing.Microbenchmarks.dll -f * --validate-fast" exited with code 1.
```

## Stacktrace

n/a

## Logs

```text
(NETCORE_ENGINEERING_TELEMETRY=Build) The command "dotnet D:\a\_work\1\s\artifacts\bin\Microsoft.AspNetCore.Routing.Microbenchmarks\Release\net10.0\Microsoft.AspNetCore.Routing.Microbenchmarks.dll -f * --validate-fast" exited with code 1.
```

## Build

https://dev.azure.com/dnceng-public/public/_build/results?buildId=1016977
https://dev.azure.com/dnceng-public/public/_build/results?buildId=1019452
https://dev.azure.com/dnceng-public/public/_build/results?buildId=1020813