Clean stack for uninitialized variables inside GetKV3Defaults

[vibecode2]

Welp, another attempt, the way GetKV3Defaults works is it creates the schema class object on stack temporarily to dump the variables from it, but there are certain uninitialized variables that pick the values from dirty previous thread stack and never zeroes them out, so we force this clean up manually before calling GetKV3Defaults function

The uninitialized variables will just be 0