Improve DB qeury performance to get all projects in namespace for security policies

Description

While working on Add migration to re-sync scan result policies f... (!116608 - merged) we noticed that the query to get all projects in a namespace from security_orchestration_policy_configuration was not efficient for namespaces that has a lot of projects. InOperatorOptimization was suggested to improve the query.

We use the same inefficient query in 2 places:

• Security::SecurityOrchestrationPolicies::SyncScanResultPoliciesService
• Security::OrchestrationPolicyRuleScheduleNamespaceWorker

We looked into using InOperatorOptimization but it didn't improve the query performance (!138647 (closed)).

We will try to find other ways to improve it.