add upgrade connector tests

[arihant-confluent]

Problem

Solution

Does this solution apply anywhere else?

• yes
• no

If yes, where?

Test Strategy

Testing done:

• Unit tests
• Integration tests
• System tests
• Manual tests

Release Plan

[cla-assistant]

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1 out of 2 committers have signed the CLA.

✅ amitr17
❌ arihant-confluent
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