OD 1.2.0 has same bug

When I use Kibana of Opendistro 1.2.0, “[esaggs] > Internal Server Error” is occured.

This is same bug, I think.

[Bug][7.2]Pie chart [esaggs] > Internal Server Error when using “group other values in separate bucket” #39654

Please rebase Elasticsearch after 7.2.1