chore: replace live r8.im registry with local test registry #8185

Job	Run time
Detect changes	7s
Build SDK	25s
Build coglet wheel	1m 33s
Compute test shards	5s
Lint Go	23s
Format Go	33s
Build cog CLI	48s
Test Go (ubuntu-latest)	42s
Test Go (macos-latest)	46s
Validate coglet version	0s
Lint Rust	0s
Format Python	0s
Check LLM docs	0s
Format Rust	0s
Test Rust	0s
Lint Rust (deny)	0s
Test integration (shard 0)	5m 42s
Test integration (shard 3)	3m 43s
Test integration (shard 2)	3m 36s
Test integration (shard 1)	4m 50s
Test coglet-python (${{ matrix.python-version }})	0s
Test Python ${{ matrix.python-version }}	0s
Lint Python	-1s
CI Complete	3s
Release Dry Run	-1s
	23m 14s

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