[Enhancement] Allow build_type to be override with other values during gradle build

[peterzhuamazon]

Our current plan of RPM is built based on the tarball artifacts.
Therefore, when running OpenSearch after installing RPM and run the service, the build_type still show as tar.

% curl https://localhost:9200 -u admin:admin --insecure
{
  "name" : "fca1dd6539e3",
  "cluster_name" : "docker-cluster",
  "cluster_uuid" : "mPdCwodbTUaT9jiJx4_w9w",
  "version" : {
    "distribution" : "opensearch",
    "number" : "1.2.1",
    "build_type" : "tar",
    "build_hash" : "e3a44fa71b290fb265a94ef4297f044b9a63a762",
    "build_date" : "2021-12-11T04:22:52.398139Z",
    "build_snapshot" : false,
    "lucene_version" : "8.10.1",
    "minimum_wire_compatibility_version" : "6.8.0",
    "minimum_index_compatibility_version" : "6.0.0-beta1"
  },
  "tagline" : "The OpenSearch Project: https://opensearch.org/"
}

We would like to have an option specified during gradle build, to change this type value to something like rpm, deb or others, so that we can build a tarball artifact that has `"build_type" : "rpm", then we can use it to assemble RPM.

Thanks.

cc: @bbarani

[dblock]

This is similar to the problem that this JSON returns the version of -min, not the version of the distribution.