Reduce the visibility of the constructors in org.springframework.jdbc.datasource.init.ScriptException.

There is currently no need to use public visibility here.

Comment From: sbrannen

Hi @xiaoliang-liu,

Thank you for submitting your first PR to the Spring Framework!

There is currently no need to use public visibility here.

This is technically correct. However, if we were to make this change we would want to make similar changes to the R2DBC variant of ScriptException, DataAccessException, NestedRuntimeException, and other classes across the framework.

Furthermore, this is essentially a matter of coding style for constructors that would otherwise be public if the class in question were not abstract. As such, those constructors can be considered part of the public API for people extending those classes (even if protected would technically serve the same goal).

In light of that, we prefer to keep these constructors public.