CLI tab completion interrupted by first-run banner

### Describe the bug

It appears to be possible for the first-run banners to appear mid-tab-completion.

### To Reproduce

I believe I had `apt update dotnet-sdk-10.0` since the last time I had run a `dotnet` command on this (WSL) machine. I typed `dotnet msbuild par⇥` and got

```sh-session
❯ dotnet msbuild par
Welcome to .NET 10.0!
---------------------
SDK Version: 10.0.103

----------------
Installed an ASP.NET Core HTTPS development certificate.
To trust the certificate, run 'dotnet dev-certs https --trust'
Learn about HTTPS: https://aka.ms/dotnet-https

----------------
Write your first app: https://aka.ms/dotnet-hello-world
Find out what's new: https://aka.ms/dotnet-whats-new
Explore documentation: https://aka.ms/dotnet-docs
Report issues and find source on GitHub: https://github.com/dotnet/core
Use 'dotnet --help' to see available commands or visit: https://aka.ms/dotnet-cli
--------------------------------------------------------------------------------------
allelbuild.proj
```

### Further technical details
details of dotnet --info

❯ dotnet --info
.NET SDK:
Version: 10.0.103
Commit: c2435c3e0f
Workload version: 10.0.100-manifests.a62d7899
MSBuild version: 18.0.11+c2435c3e0

Runtime Environment:
OS Name: ubuntu
OS Version: 24.04
OS Platform: Linux
RID: ubuntu.24.04-x64
Base Path: /usr/lib/dotnet/sdk/10.0.103/

.NET workloads installed:
There are no installed workloads to display.
Configured to use workload sets when installing new manifests.
No workload sets are installed. Run "dotnet workload restore" to install a workload set.

Host:
Version: 10.0.3
Architecture: x64
Commit: c2435c3e0f

.NET SDKs installed:
9.0.113 [/usr/lib/dotnet/sdk]
10.0.103 [/usr/lib/dotnet/sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 9.0.12 [/usr/lib/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 10.0.3 [/usr/lib/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 9.0.12 [/usr/lib/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 10.0.3 [/usr/lib/dotnet/shared/Microsoft.NETCore.App]

Other architectures found:
None

Environment variables:
Not set

global.json file:
Not found

Learn more:
https://aka.ms/dotnet/info

Download .NET:
https://aka.ms/dotnet/download

- Ubuntu 24.04.1 in WSL
- Tab completions were set up using the older `local completions=("$(dotnet complete "$words")")` mechanism