[VOL-5004] - Clone unit tests to run on a v2.12 branch

[VOL-5007]
[VOL-5010]

howto/release/preparation.rst
howto/release/ci-management/index.rst
howto/release/ci-management/create_lts_view.rst
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  o Document new makefile targets added to help branch jenkins
  o jobs for release.

Change-Id: I79b27cb16a11c76417d5f6fc2458e4c2d1bee2e0
7 files changed