Finalize release 21.11

[wphicks]

• [x] Check that all Triton base container references default to latest released version
• [x] Create rXX.YY branch on GH
• [x] Check that rXX.YY branch has been mirrored to internal repo
• [x] Update scheduled nightly CI run to run against rXX.YY
• [x] Create issue to upgrade to latest cuML in next release (if new cuML version is available)
• [x] Confirm that latest CI run on main is passing
• [x] Confirm that latest CI run on rXX.YY is passing once Triton server rXX.YY has been created
• [x] Ensure that Triton server's CI for rXX.YY is running against FIL backend rXX.YY
• [x] Protect branch rXX.YY in internal repo