MDEV-28374 UBSAN signed integer overflow PROCEDURE ANALYSE (fix)

The test cases added in [1] had a > 64 character recommendation
for Optimal_fieldtype. This was the limit on output of the field.
Under cursor mode the limit was enforced truncating the output.

Raised to a 1024 character limits as a fix for the MDEV-28374
tests, which exceeds the amount needed for for the utility of
users.

Note currently the output_str_length used in analyse::change_columns
is not currently set (so is 0) until analyse::end_of_records
is called, which is later. Consequently output_str_length is 0
and the 1024 raised maximium is used. MDEV-39586 has been raised
to correct this.

[1] 6eda0af

Author: grooverdan

sql/sql_analyse.cc

@@ -1196,8 +1196,12 @@ bool analyse::change_columns(THD *thd, List<Item> &field_list)
   func_items[7]= new (mem_root) Item_proc_string(thd, "Avg_value_or_avg_length", 255);
   func_items[8]= new (mem_root) Item_proc_string(thd, "Std", 255);
   func_items[8]->set_maybe_null();
+  /*
+   * TODO MDEV-39586 need to set output_str_length for cursor retrieval
+   * earlier because currently its always 0.
+   */
   func_items[9]= new (mem_root) Item_proc_string(thd, "Optimal_fieldtype",
-                                                  MY_MAX(64,
+                                                  MY_MAX(1024,
                                                          output_str_length));
 
   for (uint i = 0; i < array_elements(func_items); i++)