Revert github.com/urfave/cli back to v1.20.0

What does this MR do?

Reverts github.com/urfave/cli dependency back to v1.20.0. It was updated with !3525 (merged) and caused a regression described at #29193 (closed).

Why was this MR needed?

Please see #29193 (comment 1039039254) for context.

What's the best way to test this MR?

What are the relevant issue numbers?

Fixes #29193 (closed)