Fix Advanced Search Opensearch detection

What does this MR do and why?

This MR fixes the logic we use in SystemCheck::App::SearchCheck and refactors it to use Gitlab::Elastic::Helper.default.server_info instead of duplicating the logic for detecting ES distribution and version.

The problem is that SystemCheck::App::SearchCheck returns incorrect distribution for Opensearch:

SystemCheck::App::SearchCheck.current_version
=> #<Gitlab::VersionInfo:0x00007fe224d0cec0 @major=1, @minor=2, @patch=4>

SystemCheck::App::SearchCheck.distribution
=> "elasticsearch"

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Related to #363714 (closed)