Fix search interceptor toast lifetime

[lukasolson]

Summary

There seems to be a bug in the toasts that doesn't allow you to specify Infinity as the lifetime. Instead, you'll see the toast for a split second and then it will disappear. While trying to find out why that's the case, I've updated the search interceptor toasts to last for 1000000 instead of Infinity.

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
• Unit or functional tests were updated or added to match the most common scenarios
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• This was checked for cross-browser compatibility, including a check against IE11

For maintainers

• This was checked for breaking API changes and was labeled appropriately

[elasticmachine]

Pinging @elastic/kibana-app-arch (Team:AppArch)

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 9a23fc3

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