remove go.mod hack when possible

[joel-bluedata]

operator-sdk v0.15.2 depends on operator-registry v1.5.7 depends on otiai10/copy v1.0.1 and otiai10/mint v1.2.4. The otiai10 code depends on bou.ke/monkey, which has a license that says it can't be used for anything.

Some cursory exploration indicates that this dependency might be solved in a later operator-sdk release; later versions of the otiai10 code do remove the bou.ke/monkey dependency and the operator-sdk dependencies eventually catch up to that. But an operator-sdk version update is too much churn for us to take on right now.

It looks like going to otiai10/copy v1.0.2 and otiai10/mint v1.3.0 would remove this dependency. It only seems to affect test code, so it should be safe for us to just force the use of those versions in our own go.mod.

Then I'll leave this issue open until the dependency through operator-sdk goes away, so that I can then remove the hack in our go.mod.