feat: allow duplicate hostname for container registries

[rapsealk]

Follow-up of lablup/backend.ai#1917.

This pull request updates to embrace duplicated hostname when creating a new container registry, as the ContainerRegistry.registry_name field is not unique.

Checklist: (if applicable)

• Mention to the original issue
• Documentation
• Minium required manager version
• Specific setting for review (eg., KB link, endpoint or how to setup)
• Minimum requirements to check during review
• Test case(s) to demonstrate the difference of before/after

[graphite-app]

Your org requires the Graphite merge queue for merging into main

Add the label “flow:merge-queue” to the PR and Graphite will automatically add it to the merge queue when it’s ready to merge. Or use the label “flow:hotfix” to add to the merge queue as a hot fix.

You must have a Graphite account and log in to Graphite in order to use the merge queue. Sign up using this link.

[github-actions]

Coverage report for ./react

St.❔	Category	Percentage	Covered / Total
🔴	Statements	5.33% (+0% 🔼)	348/6529
🔴	Branches	4.83% (+0.01% 🔼)	218/4516
🔴	Functions	3.1% (+0% 🔼)	67/2162
🔴	Lines	5.22% (+0% 🔼)	333/6377

Test suite run success

93 tests passing in 12 suites.

Report generated by 🧪jest coverage report action from ab2d0cf

[agatha197]

I'll apply this PR to https://app.graphite.dev/github/pr/lablup/backend.ai-webui/2746/feat-fetch-container-registries-with-new-nodes-query. Thank you :)