SDK 0.17.1 and later don't state their incompatibility with earlier SDK versions

[soghoyan]

Building any multi-threaded app for Zephyr v4.1.0 or earlier fails if SDK 0.17.1 or later is installed in default SDK search path.

I'm not sure if this is intended behavior, but when building Zephyr without SDK path specified, the automatic SDK search script looks for the highest compatible version, and not exactly the one specified in SDK_VERSION file. Compatibility is verified by SDK itself during find_package() call, but none of SDKs starting from 0.17.1 return incompatibility status. This breaks very useful feature of compatible SDK installation introduced in west a year ago.