Move ElasticsearchTaskHandler to the provider package

[ephraimbuddy]

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This PR fixes one of the issues listed in #9386

The ElasticsearchTaskHandler class from airflow.utils.log.es_task_handler was moved to
airflow.providers.elasticsearch.log.es_task_handler.

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[turbaszek]

@ephraimbuddy can you please take a look at the CI errors?

[ephraimbuddy]

Hi @turbaszek , what could be the cause of the backport packages CI build error? I can't seem to figure it out

[potiuk]

Look at the logs @ephraimbuddy -> the "ExternalLoggingMixin" is a bit strange as I cannot see it in the logging_mixin. Where is it from?

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Traceback (most recent call last):
File "/import_all_provider_classes.py", line 61, in import_all_provider_classes
_module = importlib.import_module(module_name)
File "/usr/local/lib/python3.6/importlib/init.py", line 126, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "", line 994, in _gcd_import
File "", line 971, in _find_and_load
File "", line 955, in _find_and_load_unlocked
File "", line 665, in _load_unlocked
File "", line 678, in exec_module
File "", line 219, in _call_with_frames_removed
File "/usr/local/lib/python3.6/site-packages/airflow/providers/elasticsearch/log/es_task_handler.py", line 34, in
from airflow.utils.log.logging_mixin import ExternalLoggingMixin, LoggingMixin
ImportError: cannot import name 'ExternalLoggingMixin'

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ERROR ENCOUNTERED!

[potiuk]

We can't use ExtenralLoggingMixin in Airflow 1.10 providers because it only appeared .... TODAY in master

[potiuk]

If we want to support ExternalLoggingMixin we should also bacport it to 1.10 but this might be a bit more complex - using Bowler refactoring (@turbaszek WDYT?)

[ephraimbuddy]

@potiuk Thanks!

[mik-laj]

@potiuk This will cherry-pick changes to the Javascript code. If you are willing, we can do it. For now, we should delete references to this class in backport packages. This will allow these classes to be used without this one new feature.

[ephraimbuddy]

These changes have been move to #9604