flow/manager: no flow timeout when hash-size < 10

Fix Flow Manager error when flows were not being timed out
in case flow.hash-size < 10.
This happened because calculation of variable rows_per_sec in
flow-manager.c rounded the value to zero.

This commit ensures that variable rows_per_sec is at least 1.

Ticket: 8710

src/flow-manager.c

@@ -800,7 +800,9 @@ static void GetWorkUnitSizing(const uint32_t rows, const uint32_t mp, const bool
     }
     /* minimum busy score is 10 */
     const uint32_t emp = MAX(mp, 10);
-    const uint32_t rows_per_sec = (uint32_t)((float)rows * (float)((float)emp / (float)100));
+    /* ensure minimum rows_per_sec is at least 1 */
+    const uint32_t rows_per_sec =
+            MAX(1, (uint32_t)((float)rows * (float)((float)emp / (float)100)));
     /* calc how much time we estimate the work will take, in ms. We assume
      * each row takes an average of 1usec. Maxing out at 1sec. */
     const uint32_t work_per_unit = MIN(rows_per_sec / 1000, 1000);