feat: PR review suggestion

Signed-off-by: Darkheir <raphael.cohen@sekoia.io>

src/query/query_parser/logical_ast.rs

@@ -162,7 +162,7 @@ impl fmt::Debug for LogicalLiteral {
                 ref pattern,
                 ref field,
             } => write!(formatter, "Regex({field:?}, {pattern:?})"),
-            LogicalLiteral::Exists { ref field } => write!(formatter, "exists:{field}"),
+            LogicalLiteral::Exists { ref field } => write!(formatter, "Exists({field})"),
         }
     }
 }

src/query/query_parser/query_parser.rs

@@ -2123,6 +2123,6 @@ mod test {
 
     #[test]
     pub fn test_exists() {
-        test_parse_query_to_logical_ast_helper("title:*", "exists:title", false);
+        test_parse_query_to_logical_ast_helper("title:*", "Exists(title)", false);
     }
 }