npm: Fix assertion to use the correct storage api
content_get
is/was [1] about the raw content not the content itself...
- [1] it's getting renamed in swh-storage!994 (closed)
Test Plan
tox
Migrated from D3729 (view on Phabricator)
content_get
is/was [1] about the raw content not the content itself...
tox
Migrated from D3729 (view on Phabricator)