textproc/py-elasticsearch5: Remove pinned urllib3 version

elasticsearch5 (this port) unnecessarily pins its urllib dependency to
< 1.23, which blocks updating urllib3 to 1.24 [1]:

./textproc/py-elasticsearch5: setup.py: 'urllib3<1.23,>=1.21.1',

The package had a history of issues/conflicts/bugs with the urllib3
dependency, ultimately resulting in the maximum version pin being
removed [2]:

https://github.com/elastic/elasticsearch-py/issues/807
https://github.com/elastic/elasticsearch-py/issues/667
https://github.com/elastic/elasticsearch-py/issues/634

This commit backports that change, a functional noop and sweeping change
in advance required for a urllib3 update, and adds TEST_DEPENDS and
a test target to support rigorous and confident QA. Switching to GitHub
sources was required as the PyPI sdist does not package tests.

The packages tests all pass with/against urllib3 1.24 installed, with an
intermittent and non-deterministic off-by-one failure in one test:

FAIL: test_all_chunks_sent (test_elasticsearch.test_helpers.TestParallelBulk)

The issue exists independent of urllib3 version. The flaky test issue was
reported upstream [3], but was not resolved.

[2] https://github.com/elastic/elasticsearch-py/commit/4352e56174b77560d2f86801cb1ad32440bb2d32
[3] https://github.com/elastic/elasticsearch-py/issues/701

PR: 229322 [1]
Approved by: portmgr (blanket: framework compliance, runtime bugfix)