Fixed issue with description of Murano OSTF tests.

Fixed description of preparation for Platform OSTF tests for Murano.

Added information about new OSTF tests and removed information
about two incorrect Murano OSTF tests with Server Farms deployment.

Change-Id: Ib36c54602b6d28313afb861495763e9857c39140
Closes-Bug: #1271952
Merge "Fixed issue with description of Murano OSTF tests."