Environment variables not being picked up during preset configuration

Nobody has claimed this yet.

### Brief Issue Summary

When configuring a project with a configuration preset, `$env{}` is not picking up environment variables defined in extension setting `cmake.environment`. Same result when setting `cmake.configureEnvironment`. In the reproducer, I would expect the output of `message(${CACHE_VARIABLE_FROM_PRESET})` to be `hello/preset`, but it just becomes `/preset`. Is this a bug or expected behavior? From https://cmake.org/cmake/help/latest/manual/cmake-presets.7.html:

> $env{}
Environment variable with name . The variable name may not be an empty string. If the variable is defined in the environment field, that value is used instead of the value from the parent environment. If the environment variable is not defined, this evaluates as an empty string.

I would expect the extension setting `cmake.environment` in this case to define the "parent" environment of the preset execution, as the environment field mentioned in the quote above is referencing to the `environment` field within the preset itself (the environment variables defined in the `environment` field in the preset file are being picked up correctly by the way). Since when I run `AN_ENV_VARIABLE=hello cmake --preset ninja` directly from CLI, behavior is as expected (output of message is `hello/preset`).

VSCode version: 1.96.4
Extension version: 1.19.52
CMake version: 3.26.4

This may be a duplicate of the issue partially described in #4218

Attached small vscode workspace reproducer:
[cmake-preset-bug.zip](https://github.com/user-attachments/files/18534820/cmake-preset-bug.zip)

Start with the attached VS Code workspace reproducer and compare the extension's preset execution using cmake.environment or cmake.configureEnvironment with direct `AN_ENV_VARIABLE=hello cmake --preset ninja`. Read the handling of CMake preset environment variables and review related issue #4218. Done means `$env{AN_ENV_VARIABLE}` expands to `hello` through the extension, matching the CLI result.

Written by the indexing model from the issue text.