Fix negative delta arguments
Fix negative delta arguments

Three attack points, all after the regular calculations:
1. Prevent negative physics timestep counts. They could occur if
   physics_jtter_fix is changed at runtime.
2. idle_step is not allowed to go below 1/8th of the input step.
   That could happen on physics_jitter_fix changes or heavily
   fluctuating performance.
3. Prevent that the idle_step modification breaks the promise
   that Engine.get_physics_interpolation_fraction() is between
   0 and 1 by doing more physics steps than the base system wants.

Fixes #26887

Co-authored-by: Hugo Locurcio <1720facb761ad1b49c72c19a004605f1a7d73bc4@hugo.pro>

vkbsb/godot,Valentactive/godot,DmitriySalnikov/godot,godotengine/godot,firefly2442/godot,Zylann/godot,ZuBsPaCe/godot,BastiaanOlij/godot,firefly2442/godot,vnen/godot,josempans/godot,vnen/godot,josempans/godot,akien-mga/godot,Valentactive/godot,Valentactive/godot,Valentactive/godot,Shockblast/godot,guilhermefelipecgs/godot,sanikoyes/godot,josempans/godot,akien-mga/godot,ZuBsPaCe/godot,BastiaanOlij/godot,ZuBsPaCe/godot,BastiaanOlij/godot,vnen/godot,vkbsb/godot,vkbsb/godot,DmitriySalnikov/godot,vkbsb/godot,sanikoyes/godot,Zylann/godot,josempans/godot,vnen/godot,josempans/godot,ZuBsPaCe/godot,guilhermefelipecgs/godot,pkowal1982/godot,Faless/godot,BastiaanOlij/godot,Zylann/godot,godotengine/godot,BastiaanOlij/godot,ZuBsPaCe/godot,godotengine/godot,Faless/godot,Zylann/godot,Faless/godot,Zylann/godot,BastiaanOlij/godot,DmitriySalnikov/godot,Zylann/godot,firefly2442/godot,Shockblast/godot,firefly2442/godot,sanikoyes/godot,Valentactive/godot,vnen/godot,guilhermefelipecgs/godot,pkowal1982/godot,firefly2442/godot,Shockblast/godot,vkbsb/godot,godotengine/godot,DmitriySalnikov/godot,guilhermefelipecgs/godot,josempans/godot,guilhermefelipecgs/godot,Valentactive/godot,sanikoyes/godot,sanikoyes/godot,guilhermefelipecgs/godot,sanikoyes/godot,DmitriySalnikov/godot,guilhermefelipecgs/godot,Faless/godot,akien-mga/godot,ZuBsPaCe/godot,DmitriySalnikov/godot,Zylann/godot,guilhermefelipecgs/godot,Shockblast/godot,pkowal1982/godot,Shockblast/godot,BastiaanOlij/godot,vnen/godot,godotengine/godot,firefly2442/godot,vnen/godot,DmitriySalnikov/godot,Shockblast/godot,Faless/godot,Zylann/godot,pkowal1982/godot,pkowal1982/godot,akien-mga/godot,Valentactive/godot,ZuBsPaCe/godot,pkowal1982/godot,sanikoyes/godot,Shockblast/godot,BastiaanOlij/godot,Faless/godot,akien-mga/godot,josempans/godot,akien-mga/godot,ZuBsPaCe/godot,Shockblast/godot,Valentactive/godot,vkbsb/godot,vnen/godot,sanikoyes/godot,akien-mga/godot,firefly2442/godot,vkbsb/godot,josempans/godot,Faless/godot,godotengine/godot,pkowal1982/godot,Faless/godot,godotengine/godot,pkowal1982/godot,akien-mga/godot,godotengine/godot,firefly2442/godot,vkbsb/godot