Integration tests for RestClient require periodic regeneration of certificates

[Ladicek]

Description

See e.g. #27320

Implementation ideas

Use the Keytool Maven plugin to generate the necessary certificates during each build, avoiding the requirement to store the certificates in the repo and hence also the need to regenerate them. See e.g. https://github.com/rhoar-qe/thorntail-test-suite/blob/master/protocols/https-2way/pom.xml

[Ladicek]

It turns out that the tests use badssl.com and so requires its certificates. Hence, the Keytool Maven plugin is useless. Fortunately, there's a Maven plugin that can obtain certificates from external sites and store them in a keystore format: https://github.com/automatictester/truststore-maven-plugin