There should always be an internal region, even if the speed is 100%.

Even if the overhang wall speed is set to 100%, and thus wouldn't normally change, the minimum layer time for overhanging walls (split off from the minimum layer time, which is the whole point of this ticket) still should take effect -- which we can't detect if the merged regions are just one big everything blob.

part of CURA-12352

Author: rburema

src/FffGcodeWriter.cpp

@@ -3112,14 +3112,16 @@ bool FffGcodeWriter::processInsets(
             {
                 AngleDegrees overhang_angle;
                 Ratio speed_factor;
+                bool chunk = true;
             };
 
             // Create raw speed regions
             const AngleDegrees overhang_step = (90.0 - wall_overhang_angle) / static_cast<double>(overhang_angles_count);
             std::vector<SpeedRegion> speed_regions;
             speed_regions.reserve(overhang_angles_count + 1);
 
-            speed_regions.push_back(SpeedRegion{ wall_overhang_angle, 1.0_r }); // Initial internal region, always 100% speed factor
+            constexpr bool dont_chunk_first = false;
+            speed_regions.push_back(SpeedRegion{ wall_overhang_angle, 1.0_r, dont_chunk_first }); // Initial internal region, always 100% speed factor
 
             for (size_t angle_index = 1; angle_index <= overhang_angles_count; ++angle_index)
             {
@@ -3136,7 +3138,7 @@ bool FffGcodeWriter::processInsets(
                                 | ranges::views::chunk_by(
                                       [](const auto& region_a, const auto& region_b)
                                       {
-                                          return region_a.speed_factor == region_b.speed_factor;
+                                          return region_a.chunk && region_b.chunk && region_a.speed_factor == region_b.speed_factor;
                                       });
 
             // If finally necessary, add actual calculated speed regions