The innodb_system data file 'ibdata1' must be writable even with full permissions set
After reading this article and getting a main idea about SELinux and Apparmor i have finally managed to solve the issue.
The solution was adding the new path of my new datadir in /etc/apparmor.d/usr.sbin.mysqld like this:
/database2/ r,
/database2/** rwk,

Now restart the apparmor service and start the mysql service.
sudo systemctl restart apparmor
sudo systemclt start mysql