dotnet.acquire can return stale runtime when offline check fails in mssql extension

### Describe the bug.

Hello everyone, I’m a contributor to the [MSSQL](https://github.com/microsoft/vscode-mssql) extension. We recently switched the extension to use the .NET Install Tool to acquire the runtime needed to start our C# out-of-proc service, which provides connection, language service, and other MSSQL functionality.

There seems to be a bug in this extension.

Example request:

```ts
await vscode.commands.executeCommand("dotnet.acquire", {
version: "10.0.7",
requestingExtensionId: "ms-mssql.mssql",
mode: "runtime",
forceUpdate: true
});
```

### Expected Behavior

- Return 10.0.7, or
- Return a compatible same-major/minor runtime with patch >= 10.0.7, or
- Fail acquisition if no compatible runtime exists and download is unavailable.

### Actual Behavior
- In the offline fallback path, getSimilarExistingInstall() appears to match only major.minor.
- That means a cached runtime such as 10.0.3 can be returned for a 10.0.7 request.
- Our extension then launches the outerproc whose runtimeconfig.json requires Microsoft.NETCore.App 10.0.7, and the launch fails.

We also saw logs where the tool reported:
```
It looks like you may be offline (can you connect to www.microsoft.com?)
```
but then successfully downloaded 10.0.7~x64. So the offline warning may be a false positive if the probe to www.microsoft.com fails while the download endpoint is reachable.

One of our users is facing this issue: https://github.com/microsoft/vscode-mssql/issues/22015#issuecomment-4341445337

While I’ve temporarily managed to unblock affected users, I expect this issue to persist whenever we update our out-of-process service and it requires a newer .NET runtime runtime. A good chunk of our users run this extension in air-gapped/firewalled environment so it is important we find some workaround.

### Please attach log file(s) here if you have any.
```
It looks like you may be offline (can you connect to www.microsoft.com?) and have no compatible installations of .NET 10.0.7 for ms-mssql.mssql.
Installation will timeout in 600 seconds.
ms-mssql.mssql requested to download the .NET Runtime.
Downloading .NET version(s) 10.0.7~x64 ....................... Done!
.NET 10.0.7~x64 executable path: c:\Users\AhmedTarek\AppData\Roaming\Code - Insiders\User\globalStorage\ms-dotnettools.vscode-dotnet-runtime\.dotnet\10.0.7~x64\dotnet.exe
```

### .NET Install Tool Version
3.0.0

### Your operating system? Please provide more detail, such as the version and or distro above.
Windows (Should happen on every OS though)

### VS Code Version
1.117.0