Remove TestcontainersPropertySource Usage

[rwinch]

With gh-49 testjars conditionally uses TestcontainersPropertySource for older versions, but before it goes GA we should consider removing TestcontainersPropertySource support

[therepanic]

In registerBeanDefinitions we check if we can use DynamicPropertyRegistrar if our Spring Boot v3.4, otherwise we use TestcontainersPropertySource. However, I am wondering how we can get rid of TestcontainersPropertySource if backward compatibility support is important to us? Thanks