Revert "Temporarily disable aarch64 openj9 builds (#1452)" (#1551)
Revert "Temporarily disable aarch64 openj9 builds (#1452)" (#1551)

This reverts commit 1b2f804b733c9f97c417e81d04bb9b0106ff044f.
AdoptOpenJDK/openjdk-build,karianna/openjdk-build,karianna/openjdk-build,AdoptOpenJDK/openjdk-build