OeX_ES-44:  Update edx-search elasticsearch.


* removes redundant doc_types from the lms/cms, replaces courseware
index with doc_types to two indices
* code polishing

* Use a new config variable for ES7 deployment. (#2226)

Co-authored-by: Golub-Sergey <1.golub.sergey.1@gmail.com>
Co-authored-by: Diana Huang <diana.k.huang@gmail.com>

* upgrade to enterprise 3.8.43

* Fix merge

* bumping enterprise version

* adding pillow constraint

* updating usage of EnterpriseCustomerBrandingConfiguration

This reverts commit 5bf54d69.

* bumping enterprise version

* fixing platform tests broken by branding config changes

ENT-3414 | During licensed enrollment revocation, unenroll the learner if no audit mode exists for the course. Otherwise, move the learner to the audit track.

ENT-3442

ENT-3520 | Define enterprise service usernames as a simple list of strings. Upgrade edx-enterprise to 3.8.27