Added arugment error when pipeline is nil

What does this MR do and why?

FindingBuilder class inside the VulnerabilityScanning module was not checking for the edge case when pipeline argument is nil for the Sbom::Occurence which was causing GlobalAdvisoryScanWorker to fail. Thus, an argument error is raised to let the AdvisoryScan job continue it's flow.

MR acceptance checklist

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Related to #437120 (closed)

added typebug label

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added 1st contribution Community contribution workflowin dev labels

assigned to @chirayu999

	1 Warning
	3079b05c: The commit body should not contain more than 72 characters per line. For more information, take a look at our Commit message guidelines.

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added linked-issue label

@gitlab-bot ready @fcatteau . Hi, can you please review this MR. Thanks!

added workflowready for review label and removed workflowin dev label

requested review from @fcatteau

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mentioned in issue gitlab-org/quality/triage-reports#15695 (closed)

added backend devopssecure labels

added sectionsec label

added 1 commit

• 3079b05c - Reordered pipeline and project

Compare with previous version

added 1 commit

• b0d89980 - Safe call operator on pipeline

Compare with previous version

added groupcomposition analysis label

added bugfunctional severity2 labels

changed milestone to %16.8

Adding proper group, type, and sev labels (as well as milestone)

changed the description