Remove Versioning V0.3.0 pre-release code and protos

[ShahabT]

What changed?

Remove unused code about versioning deprecated pre-release APIs (only v0.3.0).

Why?

The code is not used by the current implementation. The APIs previously referring to the code has been returning the following error for the last 6+ months:

Deployments are deprecated and no longer supported, use Worker Deployments instead

How did you test it?

• [x] built
• [ ] run locally and tested manually
• [ ] covered by existing tests
• [ ] added new unit test(s)
• [ ] added new functional test(s)

Potential risks

None