Use ElasticSearch 8.5.3 in Github Actions, remove Ubuntu 18

For issues #2670 and #2706.

Note: BitShares Mekong 6.1 can work with ElasticSearch version 8 already, except that

need to configure ES with xpack.security.http.ssl.enabled=false, and
the history_api::get_account_history API doesn't work, and
the es_test unit tests will fail.

This PR fixes the API and the test cases mentioned above.

[x] Fix for ES 8 key_not_found_exception: {"key":"count"} https://github.com/bitshares/bitshares-core/blob/bd440cf0cdbda06fe7b0ca833b273fbf9b1fd985/tests/elasticsearch/main.cpp#L84 Cause: cannot specify types in ES 8 (see #1997).
- [x] Type _doc is used in the elasticsearch_plugin::get_account_history() function, which is used in an API and related unit tests. I think nobody is using it in production.
- [x] Type _doc is used in the elasticsearch_plugin::get_operation_by_id() function, which is unused (added in https://github.com/bitshares/bitshares-core/pull/1725 with context).
- [x] Type _doc is used multiple times in es_test. Note that _doc is needed for the GET API, but should not be used with the SEARCH API or the COUNT API.
[x] Fix for ES 8 Wildcard expressions or all indices are not allowed when trying to delete all indices for cleanup in unit tests. Cause: different default behavior between ES 7 and ES 8.
- ES 7 (https://www.elastic.co/guide/en/elasticsearch/reference/7.17/indices-delete-index.html):
  
  To delete all indices, use _all or * . To disallow the deletion of indices with _all or wildcard expressions, set the action.destructive_requires_name cluster setting to true.
- ES 8 (https://www.elastic.co/guide/en/elasticsearch/reference/8.5/indices-delete-index.html):
  
  By default, this parameter does not support wildcards (*) or _all. To use wildcards or _all, set the action.destructive_requires_name cluster setting to false.

bitshares / bitshares-core

Use ElasticSearch 8.5.3 in Github Actions, remove Ubuntu 18 #2707