Clean up unused legacy cycle analytics components

What does this MR do?

Follow up MR to !66189 (merged), now that we are re-using the same stage table across project and group VSA, we can remove the legacy project level stage table and related components.

This MR:

• Removes the legacy project VSA stage table
• Removes the hard coded DEFAULT_STAGE_OBJECTS, VSA stages are full returned from the BE now

Screenshots or Screencasts (strongly suggested)

No visual changes

Does this MR meet the acceptance criteria?

Conformity

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• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
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Security

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• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Related to #326704 (closed)