cmd/search: fix filtering of aliases in results

By directly modifying the results array with
`results[i] = "#{name} (installed)"`, it appeared on successive
iterations that the canonical name was no longer in the array, so
aliases were not removed.

See https://github.com/Homebrew/homebrew/commit/9efe5b554ce9cf6626d9794173725f5e063e5806#commitcomment-12969631

Closes Homebrew/homebrew#43433.