[DDW-283]: Quick fix on stake pools ranking panel

[topseniors]

This PR fixed stake pools ranking panel which was showing wallet selector dropdown even when there is no wallet.
Hiding it when no wallets now.

Review Checklist

Basics

• PR has been assigned and has appropriate labels (feature/bug/chore, release-x.x.x)
• PR is updated to the most recent version of the target branch (and there are no conflicts)
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  • In Japanese
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• Text changes are proofread and approved (Jane Wild / Amy Reeve)
• Japanese text changes are proofread and approved (Junko Oda)
• UI changes look good in all themes (Alexander Rukin)
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• In case of dependency changes yarn.lock file is updated

Code Quality

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Testing

• New feature/change is covered by acceptance tests
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After Review

• Merge the PR
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• Update Slack QA thread by marking it with a green checkmark

[alan-mcnicholas]

I checked this and with zero wallets I am not seeing the dropdown as intended. After creating wallets I can see them in the dropdown with the correct balances and after deleting all wallets the UI reverts to the previous and correct state of no dropdown. Great work! :)