Remove clock tags when forwarding operations during reshading shard transfer

[ffuugoo]

Tracked in #4213.

Resharding shard transfer initializes ForwardProxy that forwards incoming updates from local shard X to remote shard Y.

Our clock tag logic does not work well enough in such case (though, it still kinda works!), so we just remove clock tags during ForwardProxy::update, if wrapped_shard and remote_shard IDs are different.

TODO (for a follow-up PR):

When ForwardProxy forwards updates from one shard to another one, it should also "split" the operation with a hashring and only forward relevant part of the operation to the remote shard. (Or, alternatively, remote shard should split incoming operations and only apply relevant part.)

It seems a lot more annoying to implement, though, so I'll leave it for a separate PR.

All Submissions:

• Contributions should target the dev branch. Did you create your branch from dev?
• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

New Feature Submissions:

1. Does your submission pass tests?
2. Have you formatted your code locally using cargo +nightly fmt --all command prior to submission?
3. Have you checked your code using cargo clippy --all --all-features command?

Changes to Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your core changes, as applicable?
• Have you successfully ran tests with your changes locally?