Adjust costs of edges in position ranking rule

To ensure good performance

milli/src/search/new/ranking_rule_graph/position/mod.rs

@@ -111,23 +111,16 @@ impl RankingRuleGraphTrait for PositionGraph {
 
 fn cost_from_position(sum_positions: u32) -> u32 {
     match sum_positions {
-        0 | 1 | 2 | 3 => sum_positions,
-        4 | 5 => 4,
-        6 | 7 => 5,
-        8 | 9 => 6,
-        10 | 11 => 7,
-        12 | 13 => 8,
-        14 | 15 => 9,
-        16 | 17..=24 => 10,
-        25..=32 => 11,
-        33..=64 => 12,
-        65..=128 => 13,
-        129..=256 => 14,
-        257..=512 => 15,
-        513..=1024 => 16,
-        1025..=2048 => 17,
-        2049..=4096 => 18,
-        4097..=8192 => 19,
-        _ => 20,
+        0 => 0,
+        1 => 1,
+        2..=4 => 2,
+        5..=7 => 3,
+        8..=11 => 4,
+        12..=16 => 5,
+        17..=24 => 6,
+        25..=64 => 7,
+        65..=256 => 8,
+        257..=1024 => 9,
+        _ => 10,
     }
 }