Rename katib DB manager

[hougangliu]

What this PR does / why we need it:

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #1004

Special notes for your reviewer:

1. Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

Release note:

---

This change is 

[johnugeorge]

Should we wait till next API release?

[hougangliu]

/test kubeflow-katib-presubmit

[hougangliu]

Should we wait till next API release?

I think this PR only changes service name, API uninvolved.

[johnugeorge]

I meant, installation via Katib repo and manifest repo will be inconsistent. I am not sure if it is a problem

[hougangliu]

I meant, installation via Katib repo and manifest repo will be inconsistent. I am not sure if it is a problem

I think there is no problem. in katib repo, we always use latest images; and in manifest repo, we use a certain tag (now it's 0.7 in manifest master). that is, when upgrade katib repo (latest images), manifest repo is not affected.

[hougangliu]

/cc @johnugeorge @gaocegege

[johnugeorge]

/lgtm

[hougangliu]

/approve

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