Fixes #6972 Prevent injecting Beacon script when DONOTROCKETOPTIMIZE is defined

[Khadreal]

Description

Fixes #6972 Prevent injecting Beacon script when DONOTROCKETOPTIMIZE is defined and allow SaaS visit

Type of change

• [x] Bug fix (non-breaking change which fixes an issue).

Detailed scenario

Steps are available in the issue https://github.com/wp-media/wp-rocket/issues/6972

Technical description

Documentation

Check for DONOTROCKETOPTIMIZE before injecting beacon and check if it's visit for SaaS

Mandatory Checklist

Code validation

• [x] I validated all the Acceptance Criteria. If possible, provide screenshots or videos.
• [x] I triggered all changed lines of code at least once without new errors/warnings/notices.
• [x] I implemented built-in tests to cover the new/changed code.

Code style

• [x] I wrote a self-explanatory code about what it does.
• [x] I protected entry points against unexpected inputs.
• [x] I did not introduce unnecessary complexity.