.NET 8 fails to detect installed ICU on Ubuntu 25.10 (aarch64)

### Description

I am running a .NET application on Linux (aarch64). The application works correctly on Ubuntu 22.04 and 24.04. However, it fails to start on Ubuntu 25.10 with the following error:

`Process terminated. Couldn't find a valid ICU package installed on the system. Please install libicu (or icu-libs) using your package manager and try again. Alternatively you can set the configuration flag System.Globalization.Invariant to true if you want to run with no globalization support. Please see https://aka.ms/dotnet-missing-libicu for more information.`

I have verified that ICU is installed:
```
aptitude search libicu
i libicu-dev - Development files for International Components for Unicode
p libicu4j-4.4-java - Library for Unicode support and internationalization
p libicu4j-java - Library for Unicode support and internationalization
i A libicu76 - International Components for Unicode
```

The application is running on .NET 8.0.25. The same application and .NET version work correctly on an x64 machine running Ubuntu 26.04.

### Reproduction Steps

1. Set up an Ubuntu 25.10 (aarch64) environment
2. Install .NET 8.0.25
3. Install ICU (`libicu`) via the package manager
4. Run a .NET application that depends on ICU

### Expected behavior

The application starts and runs successfully.

### Actual behavior

The application terminates at startup with the ICU-related error shown above.

### Regression?

_No response_

### Known Workarounds

_No response_

### Configuration

- **.NET version:** 8.0.25
- **OS:** Ubuntu 25.10
- **Architecture:** aarch64

### Other information

Setting the environment variable `DOTNET_SYSTEM_GLOBALIZATION_INVARIANT=1` allows the application to start, but it subsequently crashes with the following exception:

```
System.Globalization.CultureNotFoundException: Only the invariant culture is supported in globalization-invariant mode. See https://aka.ms/GlobalizationInvariantMode for more information. (Parameter 'name')
en-US is an invalid culture identifier.
```

Reproduce the startup failure using the listed Ubuntu 25.10 aarch64 and .NET 8.0.25 configuration, then compare it with the working Ubuntu versions and x64 environment. Start from the ICU-related startup error and verify that the application starts with normal globalization support and can create the en-US culture without relying on invariant mode.

Written by the indexing model from the issue text.