Remove page-latest-supported-java-client property (#1602)

[It's not referenced
anywhere](https://github.com/search?q=org%3Ahazelcast+page-latest-supported-java-client+language%3AAsciiDoc&type=code&l=AsciiDoc)
and OS/EE versions make more sense because there's not really a _single_
version number.

Author: JackPGreen

docs/antora.yml

@@ -24,7 +24,6 @@ asciidoc:
     page-latest-cli: '5.2021.09'
     # Must be lowercase because this is how the version appears in the docs
     page-latest-supported-mc: '6.0-snapshot'
-    page-latest-supported-java-client: '6.0.0-SNAPSHOT'
     page-latest-supported-java-client-new: '5.5.0-BETA'
     # https://github.com/hazelcast/hazelcast-go-client/releases
     page-latest-supported-go-client: '1.4.2'