[analyzer] Split alpha core Identical Expression tests (#119543)

Split the remnant test from PR #114715, "Remove alpha.core.IdenticalExpr
Checker" into seperate tests for misc-redundant-expression and
bugprone-branch-clone per review comment requests.

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Co-authored-by: einvbri <vince.a.bridgers@ericsson.com>

Author: vabridgers