Update job log getters logic

What does this MR do?

This updates the logic from the Vuex store of the job logs app to use the optional chaining operator (?.) when possible, simplifying some conditionals

#300226 (closed)

Screenshots (strongly suggested)

N/A

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content