Fix MySQL syntax error on indexation with certain attribute codes

[Beagon]

Description

Fixes an issue where the category flat indexer would throw an MySQL syntax error if an attribute_code was equal to a MySQL function.

If you have a attribute with a code called "group" the following would occur when the catalog flat data indexer tries to run:
SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'group IS NOT NULL)' at line 5, query was: UPDATE `catalog_product_flat_1_tmp_indexer` AS `et` LEFT JOIN `eav_attribute_option_value` AS `t0` ON t0.option_id = et.group AND t0.store_id = 0 LEFT JOIN `eav_attribute_option_value` AS `ts` ON ts.option_id = et.group AND ts.store_id = 1 SET `et`.`group_value` = IFNULL(ts.value, t0.value) WHERE (group IS NOT NULL)

Manual testing scenarios

Before patch:

1. Create attribute with attribute code group.
2. Add attribute to attribute set of products.
3. Run Catalog Flat Data indexer. php bin/magento indexer:reindex catalog_category_flat
4. See the error appear.

After patch:

1. Create attribute with attribute code group.
2. Add attribute to attribute set of products.
3. Run Catalog Flat Data indexer. php bin/magento indexer:reindex catalog_category_flat
4. Everything should have been successfully rebuilt.

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

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[orlangur]

Hi @Beagon, please do the following: #22113 (comment)

[Beagon]

Hi @orlangur,

I've backported the changes from 2.3-dev.

Greetings,

Robin

[orlangur]

Great @Beagon! 👍 Didn't expect it that fast taking into consideration discussion in previous PR)

[magento-engcom-team]

Hi @orlangur, thank you for the review.
ENGCOM-4860 has been created to process this Pull Request

[VasylShvorak]

✔️ QA passed

[m2-assistant]

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