fix: System status warning nav

[benjackwhite]

Problem

See https://posthog.slack.com/archives/C02E3BKC78F/p1702955886199929

Changes

• Fixes to make sure it only shows for staff users
• Adds a dedicated button for 3000 UI

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How did you test this code?

[posthog-bot]

📸 UI snapshots have been updated

6 snapshot changes in total. 0 added, 6 modified, 0 deleted:

• chromium: 0 added, 6 modified, 0 deleted (diff for shard 1)
• webkit: 0 added, 0 modified, 0 deleted

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[github-actions]

Size Change: +7 B (0%)

Total Size: 2 MB

ℹ️ View Unchanged

Filename	Size	Change
frontend/dist/toolbar.js	2 MB	+7 B (0%)

_{compressed-size-action}

[posthog-bot]

📸 UI snapshots have been updated

1 snapshot changes in total. 0 added, 1 modified, 0 deleted:

• chromium: 0 added, 1 modified, 0 deleted (diff for shard 2)
• webkit: 0 added, 0 modified, 0 deleted

Triggered by this commit.

👉 Review this PR's diff of snapshots.

[posthog-bot]

📸 UI snapshots have been updated

1 snapshot changes in total. 0 added, 1 modified, 0 deleted:

• chromium: 0 added, 1 modified, 0 deleted (diff for shard 2)
• webkit: 0 added, 0 modified, 0 deleted

Triggered by this commit.

👉 Review this PR's diff of snapshots.