select vc toolset minor version error

### Brief Issue Summary

1、I installed tooset 14.38 and 14.42

2、 default is 14.38

3、cmake tools call vcvarsall.bat and save only this table's var but diff from direct run vcvarscall.bat -vcvars_ver=14.42, don't have VSCMD_VER env var, so when CMake Tools set vars, and call cmake -T version=14.42 ,default is vars 14.38, and use 38, do not clear by msbuild , error come out

4、cmake tools do not clean env vars，this why select minor toolset version error

5、sample

6、you can install double toolset like this ,(also see https://gitlab.kitware.com/cmake/cmake/-/issues/25192#note_1534143)

7、you can run vcvarscall.bat(default is 14.38). and unset env VSCMD_VER, then cmake -T version=14.42... bug behavior like cmake tools

### CMake Tools Diagnostics

```shell

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### Debug Log

```shell

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### Additional Information

_No response_

Start by reproducing the setup with Visual C++ toolsets 14.38 and 14.42 installed, comparing direct vcvarsall.bat -vcvars_ver=14.42 with the environment captured by CMake Tools. Inspect the CMake Tools toolset-selection path and the handling of VSCMD_VER and related variables. Done means cmake -T version=14.42 uses the requested minor toolset without stale environment variables.

Written by the indexing model from the issue text.