Migrate metadata tests to use createMockMetadata (#30880)

frontend/src/metabase-lib/metadata/Database.ts

frontend/src/metabase-lib/metadata/Database.unit.spec.ts

frontend/src/metabase-lib/metadata/Field.ts

frontend/src/metabase-lib/metadata/Field.unit.spec.ts

frontend/src/metabase-lib/metadata/Metadata.ts

frontend/src/metabase-lib/metadata/Metadata.unit.spec.ts

frontend/src/metabase-lib/metadata/Schema.unit.spec.ts

frontend/src/metabase-lib/metadata/Segment.unit.spec.ts

frontend/src/metabase-lib/metadata/utils/fields.ts

frontend/src/metabase-lib/metadata/utils/models.ts

frontend/src/metabase-types/api/field.ts

frontend/src/metabase-types/api/schema.ts

frontend/src/metabase-types/api/table.ts

...base-lib/lib/queries/StructuredQuery-nesting.unit.spec.js