Revise PyPI release jobs to use a staging index

Rewrite PyPI release-verify and release-merge templates to download
distribution files from a PyPI staging index and upload the files to
a PyPI release index.  Remove the tox etc. builders from the release
jobs.  Install and upgrade python packages setuptools, twine etc.

Drop the branch/stream parameters for the pypi release templates;
only need one release-verify and one release-merge job per project.

Split the PyPI job groups because the verify & merge templates do not
accept the same arguments as release-verify & release-merge templates,
especially no stream/branch expected by release templates.

Extend release-job.sh with PyPI release features, drop the old file
pypi-tag-release.sh

Move the PyPI release features to the lf-release-jobs.(rst,yaml) files
from the lf-python-jobs.(rst,yaml) files.

Refactor the PyPI verify and merge macros and templates due to moving
out the release-verify and release-merge features.

Restore lf-python-jobs.rst to Coala processing by WriteGoodLintBear,
but turn off processing for sections with the word 'validate'.

Change-Id: Ie27071076f9c018ccf8765c9dd948a4f5c876ec9
Issue-ID: RELENG-2455, RELENG-2497
Signed-off-by: Lott, Christopher (cl778h) <cl778h@att.com>