PIM-2669: Remove backendStorage property from attribute
PIM-2669: Update CHANGELOG.md
Merge pull request #1340 from akeneo/PIM-2669

PIM-2669: Remove backendStorage property on attribute entities
PIM-2992: Update specs and UT
PIM-2992: Redefine services injecting metric factory
PIM-2992: Update CHANGELOG.md