Return >= 1 from matching_candidates_in_table if records > 0.0

Having rows >= 1.0 helps ensure that when we calculate total rows of joins
the number of resulting rows will not be less after the join.

Changes in test cases:
- Join order change for some tables with few records
- 'Filtered' is much higher for tables with few rows, as 1 row is a high
  procent of a table with few rows.

mysql-test/main/range.result

@@ -2765,7 +2765,7 @@ EXPLAIN
             "selectivity_pct": 6.730769231
           },
           "rows": 7,
-          "filtered": 6.730769157,
+          "filtered": 14.28571415,
           "index_condition": "t2.d is not null",
           "attached_condition": "(t2.d,t2.e) in (<cache>((4,4)),<cache>((7,7)),<cache>((8,8))) and octet_length(t2.f) = 1"
         }