## Problem
The release creation process was failing with 404 errors when trying to
fetch images like cadvisor:6.6.2517 from the legacy internal registry.

## Root Cause
Recent changes in the main sourcegraph repo migrated from legacy
registries to new 'revamp' registries, but the deploy repos were still
hardcoded to use the old registry.

## Solution
- Replace `us-central1-docker.pkg.dev/sourcegraph-ci/rfc795-internal`
with `us-docker.pkg.dev/sourcegraph-images/internal`
- Updated both release.yaml and batch-change/release.yaml
- Tested and confirmed images exist in the new registry

## Test Plan
- Validated that cadvisor:6.6.2517 exists in new registry but not in old
registry
- Successfully tested sg ops update-images command with new registry
- Confirmed this fixes the original 404 errors during release creation

Co-authored-by: Amp <amp@ampcode.com>

…try auth (#1264)

Set docker username and fetch the password before running docker tests

### Test plan
CI

cherry picked
0a1fd77

Closes DINF-1271

### Test plan
CI

---------

Co-authored-by: Release Bot <107104610+sourcegraph-release-bot@users.noreply.github.com>
Co-authored-by: Warren Gifford <warrenbruceg@gmail.com>
Co-authored-by: Amp <amp@ampcode.com>

)

Amp-Thread-ID:
https://ampcode.com/threads/T-29352f06-9697-493e-aeeb-8b96745fc156

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### Checklist

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* [ ] Sister
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change (if necessary, for any changes affecting pure-docker or
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* [ ] All images have a valid tag and SHA256 sum
### Test plan
tests in CI
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---------

Co-authored-by: Amp <amp@ampcode.com>