[MDEV-26722] connect table truncates table column defined as an utf8 char string - Jira

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After upgrading MariaDB from 10.4.12 to 10.4.21, we observed problems on existing connect tables:
Result set fetched
SQLWarning:

1) Code: 1105 --- Out of range value for column col1 at row 2

2) Code: 1366 --- Incorrect string value: '\xC3' for column `lanm2434`.`testconnect`.`col1` at row 2

3) Code: 1105 --- Out of range value glac� for column 'col1' at row 2

The query is:
select 'testconnect' , col1, length(col1) , char_length(col1) from lanm2434.testconnect;

Looking at the column size in bytes and chars on the table and connect table we can see difference in count for column with multi-bytes char:

select 'testtable' , col1, length(col1)  , char_length(col1) from lanm2434.testtable

union

select 'testconnect' , col1, length(col1)  , char_length(col1) from lanm2434.testconnect ;

testtable    col1   length(col1)  char_length(col1)

-----------  -----  ------------  -----------------

testtable    glace  5             5

testtable    glacé  6             5

testconnect  glace  5             5

testconnect  glac?  5             5

And, of course, the accentuated character is not printed as bytes of the character is truncated.

Steps to reproduce:

CREATE TABLE `testtable` (

  `col1` char(5)

) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO `lanm2434`.`testtable` (`col1`) VALUES ('glace');

INSERT INTO `lanm2434`.`testtable` (`col1`) VALUES ('glacé');

CREATE or REPLACE TABLE `testconnect` ENGINE=CONNECT DEFAULT CHARSET=utf8

CONNECTION='mysql://lanm2434:pppppppp@hostname:3306/lanm2434/testtable' `TABLE_TYPE`='mysql';