java/openjdk19: Bootstrap port from prebuilt package

Change the way the port is bootstrapped, by extracting a prebuild
package to the work dir, instead of installing the previous openjdk
version to the system.

Reviewed by: bofh (mentor)
Approved by: bofh (mentor)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D54608