The ornamental design for a grillbrush handle, as shown and described.
FIG. 1 is a perspective view of the grill brush handle;
FIG. 2 is a top view of the grill brush handle;
FIG. 3 is a front view of the grill brush handle
FIG. 4 is a side view of the grill brush handle;
FIG. 5 is a bottom view of the grill brush handle; and,
FIG. 6 is a rear view of the grill brush handle.
The broken lines showing bristles and the feature on the top of the handle illustrate environmental structure and a portion of the grill brush handle that form no part of the claimed design.