[Java][tests] Set-up instructions for TLS tests

[Jared La Rue (CW)]

Hi Friends,

Running into failures in org.apache.arrow.driver.jdbc.ConnectionTlsTest
when building the Flight JDBC driver.

java.io.FileNotFoundException: <blahblahblah>/testing/data/flight/cert0.pem
(No such file or directory)

Are there any instructions on how to set up one's environment in order to
get this test to run & pass?

Thanks,
Jared