This removes some custom code inherited from Cinder which was handling
the output of secret options in a bad way. This patch utilizes Oslo's
existing utilities to output the Manila configuration options securely.
Filtering will be done with the "secret=True" option flag.
Major thanks to Eric Harney for introducing this fix to Cinder.
Change-Id: I894e011680661c0b73b9592f70a6457e403f18c6
Related-Bug: #1750074