AndroidEnvironment build task doesn't work properly when environment text file changes

### Android application type

.NET Android (net7.0-android, net8.0-android, etc.)

### Affected platform version

VS 2022 17.10 P2

### Description

AndroidEnvironment environment variables aren't updated when the environment text file changes.

[AndroidEnvTest_Debug_AnyCPU_net8.0-android_Build_2024-04-01T12_13_05.9187908-04_00.binlog.txt](https://github.com/xamarin/xamarin-android/files/14840446/AndroidEnvTest_Debug_AnyCPU_net8.0-android_Build_2024-04-01T12_13_05.9187908-04_00.binlog.txt)

### Steps to Reproduce

1. Clone https://github.com/BretJohnson/AndroidEnvTest
2. Build & run it, on Android. Note that environment variables are output to Debug, e.g. ENV1=YYYY is in the Debug output on VS.
3. Update myenv.txt, say changing the first line to be ENV1=NEWVALUE. Stop & restart, which triggers a build.

Result: Note that the Debug output still has ENV1-YYYY, not the new value.

### Did you find any workaround?

No, not yet - and a workaround is what I'd most like here, so looking for hints on that.

### Relevant log output

```shell
See attached binlog (renamed to have a .txt extension so I can attach it, but it's a .binlog).
```