Refactor Cppcheck output folder creation

[vodorok]

The root folder creation might be redundant. In #3680 @whisperity suggested a new approach to do it:

• Remove root folder creation
• "Use os.makedirs instead, so it creates the parent directories, and then the other call might truly be redundant."
  This is a follow up issue to [analyzer] Cppcheck support #3680 .

[whisperity]

In general, if there are problems with how Cppcheck behaves, we should investigate the versions that need to be supported and how those versions behave, and create a hard version requirement before releasing the feature. Cppcheck is being added as a new feature, this is the time where the contract can be pulled tight.