Replace projects storage placeholder with usage-graph

What does this MR do?

It replaces the placeholder in projects' storage counter with usage-graph component.

Note: the MR doesn't include a changelog because the changes are behind :project_storage_ui feature flag.

Screenshots

before	after

How to setup and validate locally

1. Insert dummy project statistics data from rails console:

project = Project.find(<project_id>)

project.statistics.update(
  repository_size: 3900000,
  lfs_objects_size: 4800000,
  build_artifacts_size: 400000,
  pipeline_artifacts_size: 400000,
  wiki_size: 300000,
  packages_size: 3800000
)

2. Enable project_storage_ui feature flag Feature.enable(:project_storage_ui)
3. Visit /<namespace>/<project>/-/usage_quotas (make sure you've >= maintainer permission)
4. Observe the usage graph on the page

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have self-reviewed this MR per code review guidelines.
• I have followed the style guides.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)

Related to #334888