UI: Reduce text jumping for dynamic length values

Operators that use BKE_unit_value_as_string results in numbers with a
changing fractional part which frequently jumps around.

The issue became more noticeable with centrally aligned status text,
see !139507.

Address this by disabling stripping of trailing zeros for:

- `translate_dist_to_str`
  (used by object translation, extrude, rip region).
- Mesh bevel
- Inset faces
- Shrink/fatten
- Eyedropper depth sampling (e.g. in camera DOF)

Ref !140790

source/blender/editors/interface/eyedroppers/eyedropper_depth.cc

@@ -281,7 +281,7 @@ static void depthdropper_depth_sample_pt(bContext *C,
           BKE_unit_value_as_string(ddr->name,
                                    sizeof(ddr->name),
                                    double(*r_depth),
-                                   4,
+                                   -4,
                                    B_UNIT_LENGTH,
                                    scene->unit,
                                    false);

source/blender/editors/mesh/editmesh_bevel.cc

@@ -138,7 +138,7 @@ static void edbm_bevel_update_status_text(bContext *C, wmOperator *op)
   else {
     double offset_val = double(RNA_float_get(op->ptr, "offset"));
     BKE_unit_value_as_string_scaled(
-        offset_str, NUM_STR_REP_LEN, offset_val, 3, B_UNIT_LENGTH, sce->unit, true);
+        offset_str, NUM_STR_REP_LEN, offset_val, -3, B_UNIT_LENGTH, sce->unit, true);
   }
 
   PropertyRNA *prop;

source/blender/editors/mesh/editmesh_inset.cc

@@ -86,14 +86,14 @@ static void edbm_inset_update_header(wmOperator *op, bContext *C)
       BKE_unit_value_as_string(flts_str,
                                NUM_STR_REP_LEN,
                                RNA_float_get(op->ptr, "thickness"),
-                               4,
+                               -4,
                                B_UNIT_LENGTH,
                                sce->unit,
                                true);
       BKE_unit_value_as_string(flts_str + NUM_STR_REP_LEN,
                                NUM_STR_REP_LEN,
                                RNA_float_get(op->ptr, "depth"),
-                               4,
+                               -4,
                                B_UNIT_LENGTH,
                                sce->unit,
                                true);

source/blender/editors/transform/transform_mode_shrink_fatten.cc

@@ -120,7 +120,7 @@ static void applyShrinkFatten(TransInfo *t)
     if (unit.system != USER_UNIT_NONE) {
       char unit_str[64];
       BKE_unit_value_as_string_scaled(
-          unit_str, sizeof(unit_str), distance, 4, B_UNIT_LENGTH, unit, true);
+          unit_str, sizeof(unit_str), distance, -4, B_UNIT_LENGTH, unit, true);
       fmt::format_to(fmt::appender(str), "{}", unit_str);
     }
     else {

source/blender/editors/transform/transform_mode_translate.cc

@@ -164,7 +164,7 @@ static void translate_dist_to_str(char *r_str,
                                   const UnitSettings *unit)
 {
   if (unit && (unit->system != USER_UNIT_NONE)) {
-    BKE_unit_value_as_string_scaled(r_str, r_str_maxncpy, val, 4, B_UNIT_LENGTH, *unit, false);
+    BKE_unit_value_as_string_scaled(r_str, r_str_maxncpy, val, -4, B_UNIT_LENGTH, *unit, false);
   }
   else {
     /* Check range to prevent string buffer overflow. */