openharmony: Drop distro override in java-tools.include

This allows using java-tools.inc, and thus openharmony-standard,
hapsigner-native and packing-tool-native recipes with any distro configuration.
These recipes should only be used for OpenHarmony enabled distro configurations
anyway.

Signed-off-by: Esben Haabendal <esben.haabendal@huawei.com>