Fix T110 violation for database client

T110 requires methods, which calls GET, should be "list_<resource>s"
or "show_<resource>" as these names for consistency.
In addition, the other service clients doesn't contain "_details" on
the method names.
So this patch renames get_db_flavor_details to show_db_flavor on
database client.

Partially implements blueprint consistent-service-method-names

Change-Id: Ia0b509ad9c4413c3ea9910e06d7c60c0c4f6896e
4 files changed