[CI] Remove duplicate jobs (#5602)

All of these things are already tested in Github Actions:
https://github.com/paritytech/polkadot-sdk/blob/b3c2a25b

/.github/workflows/checks-quick.yml#L50

Q: the `job-starter` seems to be used by tests, so am keeping it, but
not sure how useful it is.

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Co-authored-by: Alexander Samusev <[email protected]>
Co-authored-by: alvicsam <[email protected]>