Remove the old implementation of dashboard

[warjiang]

What would you like to be added:
Remove the old implementation code of dashboard, clean the code.

Why is this needed:
The old implementation of dashboard will make the contributor confused, the new implementaion is more powerful than the old one, which have clear roadmap, so we prepare to remove the old code before the release the brand new version of karmada dashboard.

[warjiang]

/assign

[warjiang]

/assign jayesh9747

[karmada-bot]

@warjiang: GitHub didn't allow me to assign the following users: jayesh9747.

Note that only karmada-io members with read permissions, repo collaborators and people who have commented on this issue/PR can be assigned. Additionally, issues/PRs can only have 10 assignees at the same time.
For more information please see the contributor guide

In response to this:

/assign jayesh9747

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[warjiang]

@jayesh9747

[warjiang]

/unassign

[jayesh9747]

@warjiang can you assign me this issue?

[jayesh9747]

/assign

[warjiang]

/assign @jayesh9747