[8.x] [SecuritySolution] Fix serviceEntityStoreEnabled experimental f…

…lag initial value (#203573) (#203608)

# Backport

This will backport the following commits from `main` to `8.x`:
- [[SecuritySolution] Fix serviceEntityStoreEnabled experimental flag
initial value (#203573)](#203573)

<!--- Backport version: 9.4.3 -->

### Questions ?
Please refer to the [Backport tool
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Fix serviceEntityStoreEnabled experimental flag initial value
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Co-authored-by: Pablo Machado <[email protected]>

x-pack/plugins/security_solution/common/experimental_features.ts

@@ -246,7 +246,7 @@ export const allowedExperimentalValues = Object.freeze({
   /**
    * Enables the Service Entity Store. The Entity Store feature will install the service engine by default.
    */
-  serviceEntityStoreEnabled: true,
+  serviceEntityStoreEnabled: false,
 
   /**
    * Enables the siem migrations feature