Check for other DataSource unwrapping calls

[philwebb]

The update in #15206 may apply to other areas of the code. We should do a sweep to check.

[wilkinsona]

The instanceof checks in DataSourcePoolMetadataProvidersConfiguration might be problematic.

[snicoll]

There are potentially others, non Tomcat datasource related. I've started to work on this in the base PR and will adapt here after.

[snicoll]

There are some instanceof checks still, see #15316 (comment)