Fix line count accidwentally swapped with pre-5.6

Miraculously, **this did not cause *any* test to consistently fail,
except for an MTR internal check difference from
`rpl.rpl_upgrade_master_info_section`,
from how the server `DEFAULT` is different from the MTR default.

Author: ParadoxV5

sql/rpl_info_file.h

@@ -305,7 +305,7 @@ struct Info_file
       Set the default after parsing: While std::from_chars() does not replace
       the output if it failed, it does replace if the line is not fully spent.
     */
-    size_t line_count= i ? static_cast<size_t>(val) : default_line_count;
+    size_t line_count= i ? default_line_count: static_cast<size_t>(val);
     for (; i < line_count; ++i)
     {
       int c;