What warning are you getting? I'm not getting any, regardless log_warnings.
Please paste the warning and also provide your cnf file(s).

>What warning are you getting?
2019-10-14 6:24:43 13 [Warning] InnoDB: Cannot add field `Token` in table `zissystem`.`webproviderprofiledef` because after adding it, the row size is 8345 which is greater than maximum allowed size (8126) for a record on index leaf page.
2019-10-14 6:27:16 46 [Warning] InnoDB: Cannot add field `DeleterZISSourceDescData` in table `eventmonitor`.`eustatus00000100005_pending` because after adding it, the row size is 8477 which is greater than maximum allowed size (8126) for a record on index leaf page.
2019-10-14 6:27:16 65 [Warning] InnoDB: Cannot add field `DeleterZISSourceDescData` in table `eventmonitor`.`eustatus00000100020_pending` because after adding it, the row size is 8477 which is greater than maximum allowed size (8126) for a record on index leaf page.
2019-10-14 6:27:16 67 [Warning] InnoDB: Cannot add field `DeleterZISSourceDescData` in table `eventmonitor`.`eustatus00000100006_pending` because after adding it, the row size is 8478 which is greater than maximum allowed size (8126) for a record on index leaf page.
2019-10-14 6:27:16 76 [Warning] InnoDB: Cannot add field `DeleterZISSourceDescData` in table `eventmonitor`.`eustatus00000100002_pending` because after adding it, the row size is 8478 which is greater than maximum allowed size (8126) for a record on index leaf page.
2019-10-14 6:27:16 70 [Warning] InnoDB: Cannot add field `DeleterZISSourceDescData` in table `eventmonitor`.`eustatus00000100040_pending` because after adding it, the row size is 8477 which is greater than maximum allowed size (8126) for a record on index leaf page.
2019-10-14 6:27:16 79 [Warning] InnoDB: Cannot add field `DeleterZISSourceDescData` in table `eventmonitor`.`eustatus00000100035_pending` because after adding it, the row size is 8477 which is greater than maximum allowed size (8126) for a record on index leaf page.
2019-10-14 6:27:16 69 [Warning] InnoDB: Cannot add field `DeleterZISSourceDescData` in table `eventmonitor`.`eustatus00000100031_pending` because after adding it, the row size is 8477 which is greater than maximum allowed size (8126) for a record on index leaf page.
2019-10-14 6:27:16 73 [Warning] InnoDB: Cannot add field `DeleterZISSourceDescData` in table `eventmonitor`.`eustatus00000100039_pending` because after adding it, the row size is 8477 which is greater than maximum allowed size (8126) for a record on index leaf page.
... my.ini R2224WFTZS.zip

In the attachment is errorlog of the last 20 minutes to show you how many warnings are written since 10.3.x into the errorlog.

migra,

If set to 0, warnings are not logged.*
https://mariadb.com/kb/en/library/server-system-variables/#log_warnings

This was an inaccuracy in the documentation that has already been fixed.

I've requested a way to suppress those warnings in the error log in MDEV-20832.

In the mean time, you can already suppress these warnings if you are willing to fix the tables involved. You may be able to do so by converting them to the DYNAMIC row format and by making sure that all varchar columns are at least as long as 256 bytes. See the following page for details:

https://mariadb.com/kb/en/library/troubleshooting-row-size-too-large-errors-with-innodb/

migra,

For the case of the test_pending table schema in the issue description, it is sufficient to convert the table to the DYNAMIC row format.

https://mariadb.com/kb/en/library/troubleshooting-row-size-too-large-errors-with-innodb/#converting-the-table-to-the-dynamic-row-format

For example:

ALTER TABLE `test_pending` ROW_FORMAT=DYNAMIC;

You may want to try the same fix for other affected tables as well. For example:

ALTER TABLE `zissystem`.`webproviderprofiledef`  ROW_FORMAT=DYNAMIC;

ALTER TABLE `eventmonitor`.`eustatus00000100005_pending` ROW_FORMAT=DYNAMIC;

...

ALTER TABLE `eventmonitor`.`eustatus00000100031_pending` ROW_FORMAT=DYNAMIC;

ALTER TABLE `eventmonitor`.`eustatus00000100039_pending` ROW_FORMAT=DYNAMIC;

These warnings can be inappropriately logged due to MDEV-20949.

It was a incorrect documentation that was fixed.