etcd: fix json unmarshall error and sources not found after upgrade to 2.0.2 (#1635)

[ti-chi-bot]

This is an automated cherry-pick of #1635

What problem does this PR solve?

part of #1636

Info struct changed in v2.0.2, but forgot to update etcd value.

close #1644
upgrade etcd before scheduler start

What is changed and how it works?

Try unmarshall and convert old info to new info if unmarshall error happened.
Try upgrade etcd key before scheduler start.

Check List

Tests

• Unit test
• upgrade test

[lance6716]

/lgtm

[ti-chi-bot]

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[lance6716]

upgrade from V1 failed

E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?
  404  Not Found [IP: 151.101.210.132 80]

[lance6716]

but we already apt-get update, merge it anyway

[lance6716]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: ed92223