Prior to this commit, if the "Texture Mask" stencil was reset, this would call the `brush.stencil_reset_transform` operator with the `mask` parameter set to `True`. Subsequent clicks, even on the "Texture" stencil "Reset Transform" button would still pass `True` to the underlying C++ API, even though the `mask` property was left uninitialized. This commit sets the parameter to False explicitly to fix this bug. Pull Request: https://projects.blender.org/blender/blender/pulls/132001