[Connectors] Include manage_connector privilege in generated api keys

[jedrazb]

Summary

We introduced manage_connector privilege in ES: elastic/elasticsearch#110128

Let's use it for new generated API keys for connectors.

Note: this privilege was merged to ES yesterday, so CI might fail if the ES image was not updated yet.

Checklist

Delete any items that are not applicable to this PR.

• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• Documentation was added for features that require explanation or tutorials
  • We will add this privilege in ES docs
• Unit or functional tests were updated or added to match the most common scenarios

[sphilipse]

lgtm

[jedrazb]

I will wait with merging until we can verify with up-to-date ES docker image, even if it implies merging tomorrow

[kibana-ci]

💚 Build Succeeded

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• Commit: 7947eb6

Metrics [docs]

✅ unchanged

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@elasticmachine merge upstream

[jedrazb]

All good! Validated with "Generate API key" button on the latest stack snapshot Merging