Add minima for retraction prime speed

Otherwise the automated inheritance function makes it negative sometimes.

Contributes to issue #6806.

resources/quality/imade3d_jellybox_2/jb2_global_coarse.inst.cfg

@@ -35,7 +35,7 @@ retraction_combing = noskin
 retraction_hop_enabled = True
 retraction_min_travel = =machine_nozzle_size * 3
 retraction_retract_speed = =retraction_speed
-retraction_prime_speed = =retraction_speed - 30
+retraction_prime_speed = =max(retraction_speed - 30, 5)
 roofing_layer_count = 1
 skin_line_width = =line_width * 1.2
 skin_outline_count = 2

resources/quality/imade3d_jellybox_2/jb2_global_fine.inst.cfg

@@ -35,7 +35,7 @@ retraction_combing = noskin
 retraction_hop_enabled = True
 retraction_min_travel = =machine_nozzle_size * 3
 retraction_retract_speed = =retraction_speed
-retraction_prime_speed = =retraction_speed - 30
+retraction_prime_speed = =max(retraction_speed - 30, 5)
 roofing_layer_count = 1
 skin_line_width = =line_width * 1.2
 skin_outline_count = 2

resources/quality/imade3d_jellybox_2/jb2_global_normal.inst.cfg

@@ -35,7 +35,7 @@ retraction_combing = noskin
 retraction_hop_enabled = True
 retraction_min_travel = =machine_nozzle_size * 3
 retraction_retract_speed = =retraction_speed
-retraction_prime_speed = =retraction_speed - 30
+retraction_prime_speed = =max(retraction_speed - 30, 5)
 roofing_layer_count = 1
 skin_line_width = =line_width * 1.2
 skin_outline_count = 2

resources/quality/imade3d_jellybox_2/jb2_global_ultrafine.inst.cfg

@@ -35,7 +35,7 @@ retraction_combing = noskin
 retraction_hop_enabled = True
 retraction_min_travel = =machine_nozzle_size * 3
 retraction_retract_speed = =retraction_speed
-retraction_prime_speed = =retraction_speed - 30
+retraction_prime_speed = =max(retraction_speed - 30, 5)
 roofing_layer_count = 1
 skin_line_width = =line_width * 1.2
 skin_outline_count = 2