Fix race condition while creating scan_result_policy_read

What does this MR do and why?

Similar to Handle race condition in approval rule creation... (!190155 - merged), while rolling out use_approval_policy_rules_for_approval_rules FF, there was a race-condition with creating scan_result_policy_reads when there are concurrent execution of workers. This MR adds an additional check before creating scan_result_policy_reads.

This MR also adds logs when ApprovalRules::CreateService & ApprovalRules::UpdateService fails as we are currently not doing error-handling.

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Addresses #538759 (closed)