feat: don't require editing MariaDB configuration to setup frappe (backport #25609)

[mergify]

In order to gain flexibility to write Dokos install script and packages, the --no-setup-db parameter of the bench new-site command is a very great improvement!

However, in order to free installation from the need of adding to /etc/mysql/my.cnf

[mysqld]
character-set-client-handshake = FALSE
character-set-server = utf8mb4
collation-server = utf8mb4_unicode_ci

[mysql]
default-character-set = utf8mb4

the function create_database should pass these requirements : CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci
and thus we don't need to check GLOBAL mysql VARIABLES.

With this PR, the following :

sudo mysql -u root -e "CREATE USER '$db_name'@'localhost' IDENTIFIED BY '$db_pwd';"
sudo mysql -u root -e "CREATE DATABASE IF NOT EXISTS $db_name CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;"
sudo mysql -u root -e "GRANT ALL PRIVILEGES ON $db_name . * TO '$db_name'@'localhost';"
sudo mysql -u root -e "FLUSH PRIVILEGES;"

bench new-site $site_name --db-name $db_name --db-password $db_pwd --no-setup-db --admin-password $admin_pwd

could work without changing /etc/mysql/my.cnf .
Actually, we could remove from documentation the requirement to change /etc/mysql/my.cnf

---

This is an automatic backport of pull request #25609 done by Mergify.

[mergify]

Cherry-pick of ed01fc3 has failed:

On branch mergify/bp/version-15-hotfix/pr-25609
Your branch is up to date with 'origin/version-15-hotfix'.

You are currently cherry-picking commit ed01fc3b26.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   frappe/database/db_manager.py

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   frappe/database/mariadb/setup_db.py

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[Thatoo]

Now that PR #25759 has been merged, this one could be merged too. 😄

[frappe-pr-bot]

🎉 This PR is included in version 15.21.0 🎉

The release is available on GitHub release

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