Fix Opensearch compatibility check

What does this MR do and why?

In this MR we are doing a couple of things:

• Match SystemCheck::App::SearchCheck with the stated Opensearch versions supported (1.x or later)
• Switch ee/spec/lib/system_check/app/search_check_spec.rb to using fast_spec_helper, which drastically improve performance

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Related to #378958 (closed)