Drop package prefixes in table created in "metadata" schema

Apache SIS 0.8 creates tables in the "SpatialMetadata" database with the exact same name as defined in the UML of the ISO 19115 metadata standard. All those names have a package prefixes (e.g. "CI_" in "CI_Citation"). However recent ISO standards tends to drop the package prefixes. For example "CS_CoordinateSystem" in ISO 19111:2007 become "CoordinateSystem" in ISO 19111:2018. In anticipation for such change in ISO metadata standard, or for making the "metadata" schema easier to read even if future ISO 19115 does not apply this change, we drop the package prefixes in names of the tables created by the org.apache.sis.metadata.sql.MetadataWriter class.