Minor: use checked-in genesis for --chain=manta

[Garandor]

Description

First row generated locally by this commit, second from 402 CI job, third from checked-in genesis.

cargo run --release -- build-spec --chain manta --raw > ./manta-genesis.json
cargo run --release -- export-genesis-state --chain manta > ./manta-genesis.state
cargo run --release -- export-genesis-wasm --chain manta > ./manta-genesis.wasm
❯ sha256sum manta-genesis*
b50ea39241941e9bd88a2a51aaa4f0ae1ce86a11909554c3e44b46882b8ea8b7  manta-genesis.json
3caa9f599f578d7f7a3329fdf75785c6f0b9cedf62866b0d62cca77c0647bef6  manta-genesis.state
cd9a1c176685999458f99d6df5cc3d0937f65db9eb33632cf8100af378da3184  manta-genesis.wasm

❯ sha256sum Genesis-from-CI/manta-genesis.*
b50ea39241941e9bd88a2a51aaa4f0ae1ce86a11909554c3e44b46882b8ea8b7  Genesis-from-CI/manta-genesis.json
3caa9f599f578d7f7a3329fdf75785c6f0b9cedf62866b0d62cca77c0647bef6  Genesis-from-CI/manta-genesis.state
cd9a1c176685999458f99d6df5cc3d0937f65db9eb33632cf8100af378da3184  Genesis-from-CI/manta-genesis.wasm

❯ sha256sum genesis/manta-genesis.json 
b50ea39241941e9bd88a2a51aaa4f0ae1ce86a11909554c3e44b46882b8ea8b7  genesis/manta-genesis.json

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• 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
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• Re-reviewed Files changed in the Github PR explorer.

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.

[ferrell-code]

We can delete manta_genesis.rs. Its in our git history, so we can always find it if needed.

It doesn't matter much to me, but I'm not sure I see the benefit of keeping the dead code (I think I remember we discussed keeping this)

[Garandor]

I'm not sure I see the benefit of keeping the dead code

It was decided to keep it in order to easily and quickly see the genesis configuration as this info can't be gained from the raw genesis file. IMO we should keep it around at least until after launch when the accounts listed become no longer relevant