Remove Milestones and releases candidate releases versions from SDKMAN

[sdelamo]

I think we should we release Milestones and releases candidate versions from SDKMAN

@micronaut-projects/core-developers thoughts?

[wetted]

I agree with removing them. Last time I used SDKMAN I wondered why they were all there, especially the old ones.

[timyates]

I agree 👍

[melix]

Fine by me too