chore: replace live r8.im registry with local test registry #8187

Job	Run time
Detect changes	6s
Compute test shards	6s
Build coglet wheel	1m 27s
Test Go (macos-latest)	1m 4s
Lint Go	23s
Format Go	33s
Test Go (ubuntu-latest)	39s
Build SDK	33s
Build cog CLI	49s
Check LLM docs	0s
Lint Rust (deny)	0s
Test Rust	0s
Format Python	0s
Validate coglet version	0s
Lint Rust	0s
Format Rust	0s
Test integration (shard 0)	5m 10s
Test integration (shard 1)	4m 12s
Test integration (shard 2)	4m 9s
Test integration (shard 3)	4m 2s
Test Python ${{ matrix.python-version }}	0s
Lint Python	0s
Test coglet-python (${{ matrix.python-version }})	0s
CI Complete	4s
Release Dry Run	-1s
	23m 16s

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