Update prerequisites for security dashboard to appear

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What does this MR do?

Specifies that for the Security Dashboard to appear/activate for a project it must have detected at least one vulnerability. If there are no detected vulnerabilities in a given project, the dashboard does not appear. This is confusing for customers who review the prerequisites section and fulfil the requirements but do not see the dashboard as they have not yet detected a vulnerability.

For confirmation:

1. Create empty project in SaaS Ultimate group with a test.rb (to trigger SAST job) file in it
2. Enable SAST via simple CI config:

include:
  - template: Security/SAST.gitlab-ci.yml

stages:
  - test

3. Run successful scan against main branch
4. Confirm prerequisites, and observe dashboard does not load/activate
5. Add a vulnerability to the project:

# create ruby file oopsie.rb with this code:

class BenefitFormsController < ApplicationController

  def index
    @benefits = Benefits.new
  end

  def download
   begin
     path = params[:name]
     file = params[:type].constantize.new(path)
     send_file file, disposition: "attachment"
   rescue
     redirect_to user_benefit_forms_path(user_id: current_user.id)
   end
  end

  def upload
    file = params[:benefits][:upload]
    if file
      flash[:success] = "File Successfully Uploaded!"
      Benefits.save(file, params[:benefits][:backup])
    else
      flash[:error] = "Something went wrong"
    end
    redirect_to user_benefit_forms_path(user_id: current_user.id)
  end

end

6. Wait for SAST scan to finish then observe dashboard appears as expected

Related issues

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