Introduce feature flag for triggering calls to Secret Detection Service

This issue proposes to add a feature flag before calling the Secret Detection Service to run secret detection scans. It serves multiple benefits as follows:

1. In case service becomes unresponsive, instead of disrupting customer workflows, we could turn off the FF and temporarily use the gem-based approach to trigger SD scans as a fallback.
2. If the service's infrastructure-related issues require service downtime, we could turn off the FF and temporarily use the gem-based approach to trigger SD scans until the issue is resolved.
3. When we are ready to roll out the service into active mode, we could gradually introduce the feature flag to limit the impact of any potential failures.