Fix plugin doc generation for opendev transition

Update the server to opendev and update paths for gitea, along with
any other references.

Switch to a blacklist where we just remove stackforge; this leaves all
the new namespaces like x/ and starlingx/ being checked.

Use a common session for checking for the plugin file which makes it a
*lot* faster.

Remove unsed "plugins" array variable

Regenerate the file

Change-Id: Ie3e615ba352a389da22e129c5c67cf6abd8cfdc8
3 files changed