this pull restores the ability to recover from database failures in gsql backends
fixes #3583 (failed constraint may never lead to a crash)
Revert "Throw correct exception on temporary DB issue"
This reverts commit 90843c3.
Revert "Add remark about not removing the throw"
This reverts commit 7da873e.
Revert "Make pdns die on fatal error"
This reverts commit ff1ac70.