Update API Fuzzing image name to use SECURE_ANALYZERS_PREFIX

What does this MR do?

Adds the variable SECURE_ANALYZERS_PREFIX to API Fuzzing image. This variable is used by Security Analyzers to support offline deployment. It allows offline users to easily change the image registry used by all Secure analyzers with one variable.

• Use SECURE_ANALYZER_PREFIX
• Remove -engine suffix

Related to #325731 (closed)

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• This change should be backward compatible
• Tests have been updated to reflect this change
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• 📋 Does this MR need a changelog?

  • I have included a changelog entry.
  • I have not included a changelog entry because this change is backward compatible, there is a changelog entry that explains this change. This change has been applied in this merge request, the only difference it is that the updated template was the API-Fuzzing.latest.gitlab-ci.yml and this merge request is updating API-Fuzzing.gitlab-ci.yml. In 14.0, API-Fuzzing.gitlab-ci.yml will be replaced with API-Fuzzing.latest.gitlab-ci.yml. Thus, adding the changelog entry now will pretty much duplicate the changelog entry because it is the same change.

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