🐛 Fix Dockerfile by copying tmc directory into build directory

[embik]

Summary

Since #2202, container image builds were broken (https://github.com/kcp-dev/kcp/actions/workflows/kcp-image.yaml) because it moved tmc-related logging constants into a directory that was previously not copied as part of the Dockerfile COPY directives:

pkg/syncer/namespace/namespace_downstream_process.go:33:2: no required module provides package github.com/kcp-dev/kcp/tmc/pkg/logging; to add it:
	go get github.com/kcp-dev/kcp/tmc/pkg/logging

This PR should fix that, re-enabling image builds (locally and via GitHub actions).

[openshift-ci]

Hi @embik. Thanks for your PR.

I'm waiting for a kcp-dev member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ncdc

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