Test auto-reconfig for postgresql

- Use the "uri" attribute to compute the expected datasource url, since
  Elephantsql service doesn't not expose the "jdbcUrl" attribute
- Morph the "url" attribute to a simpler, consistent form suitable for testing
Add tests and extract out JDBC URL normalization

This change adds tests for the new (and changed) code that was added
to support testing of Postgres auto-reconfiguration.  The algorithm
used to normalize the JDBC URL, both returned from the applications
and returned from the services, has been extracted to a utility used
for both cases.  This should ensure that they stay in sync.

[#61931886] [Finishes #3]
Merge 61931886-postgres to master

[Completes #61931886]