Allow MySQL sites to set the 'sql_mode' in the database

Problem/Motivation

For MySQL databases is the 'sql_mode' set on every page request. This is an unnecessary database call and it makes Drupal a little bit slower than is needed.

Proposed resolution

Allow site owners to set the 'sql_mode' in the database with the command: SET GLOBAL sql_mode = 'ANSI,TRADITIONAL';. See: https://dev.mysql.com/doc/refman/8.0/en/sql-mode.html

Remaining tasks

See: 🐛 Use READ COMMITTED by default for MySQL transactions Fixed . The difference is that there an option is added and here is an option suppressed.

User interface changes

None.

API changes

None.

Data model changes

None.

Release notes snippet

None.