2.3 to 2.6 migration guides are missing steps

Due to missing steps in each of these guides it's not possible to perform this multi-upgrade path without encountering issues. Some of those issues have been reported previously and are documented in KCS and the related JIRA issues. However, there may be some steps still not found which are missing and the attached document is an attempt to fix all those issues whilst getting the state of the configuration at the end of each upgrade into an equal state as a fresh installation.

It's required to review the steps in the document as soon as possible so that the upgrade can be unblocked.