Remove legacy storage

[Dengjianping]

Description

Closes #1273

Before we can approve this PR for merge, please make sure that all the following items have been checked off:

• [ ] Connected to an issue with discussion and accepted design using zenhub "Connect issue" button below
• [ ] Added one label out of the L- group to this PR
• [ ] Added one or more labels from the A- and C- groups to this PR
• [ ] Explicitly labelled A-calamari and/or A-manta if your changes are meant for/impact either of these (CI depends on it)
• [ ] Re-reviewed Files changed in the Github PR explorer.
• [ ] Add A-integration-test-checks to run start-integration-test-checks (Required)
• [ ] Add A-benchmark-checks to run start-benchmark-check (Required)
• [ ] Add A-unit-test-checks to run start-unit-test-checks (Required)
• [ ] Add A-congestion-test-checks to run start-integration-test-checks (Optional)

Situational Notes:

• If adding functionality, write unit tests!
• If importing a new pallet, choose a proper module index for it, and allow it in BaseFilter. Ensure every extrinsic works from front-end. If there's corresponding tool, ensure both work for each other.
• If needed, update our Javascript/Typescript APIs. These APIs are officially used by exchanges or community developers.
• If modifying existing runtime storage items, make sure to implement storage migrations for the runtime and test them with try-runtime. This includes migrations inherited from upstream changes, and you can search the diffs for modifications of #[pallet::storage] items to check for any.