Heat operator uses the helper function `GetDatabaseByName()` in multiple places. It is necessary to replace all usage of this helper function with `GetDatabaseByNameAndAccount` instead.

This is required to unblock openstack-k8s-operators dependencies and currently blocks us:
https://github.com/openstack-k8s-operators/heat-operator/pull/336

Necessitated by the removal of the old helper function:
https://github.com/openstack-k8s-operators/mariadb-operator/commit/e140f47424248c831033d8e6e8b536126b75a8fa

First one was done here:
https://github.com/openstack-k8s-operators/heat-operator/commit/316002f57425671e53f2512be1cfe8512cc169dd#diff-dc46da6f97cbd197e2808f95d64e4a2c46acc2356aaad651ef772982aee38a72L337

But the other controllers in Heat operator are also using this function and need refactoring.