Create Posthog instance only whe user consent is given, to avoid pinging Posthog server at startup when consent is not given.

Note that feature flag will not work, but for now they are not used.
All the `?.takeIf { userConsent == true }` could be removed with this change, but let's keep them for safety...

vector/src/main/java/im/vector/app/features/analytics/impl/DefaultVectorAnalytics.kt

@@ -41,21 +41,25 @@ private val IGNORED_OPTIONS: Options? = null
 
 @Singleton
 class DefaultVectorAnalytics @Inject constructor(
-        postHogFactory: PostHogFactory,
+        private val postHogFactory: PostHogFactory,
         private val sentryAnalytics: SentryAnalytics,
-        analyticsConfig: AnalyticsConfig,
+        private val analyticsConfig: AnalyticsConfig,
         private val analyticsStore: AnalyticsStore,
         private val lateInitUserPropertiesFactory: LateInitUserPropertiesFactory,
         @NamedGlobalScope private val globalScope: CoroutineScope
 ) : VectorAnalytics {
 
-    private val posthog: PostHog? = when {
+    private var posthog: PostHog? = null
+
+    private fun createPosthog(): PostHog? {
+        return when {
             analyticsConfig.isEnabled -> postHogFactory.createPosthog()
             else -> {
                 Timber.tag(analyticsTag.value).w("Analytics is disabled")
                 null
             }
         }
+    }
 
     // Cache for the store values
     private var userConsent: Boolean? = null
@@ -150,6 +154,7 @@ class DefaultVectorAnalytics @Inject constructor(
         userConsent?.let { _userConsent ->
             when (_userConsent) {
                 true -> {
+                    posthog = createPosthog()
                     posthog?.optOut(false)
                     identifyPostHog()
                     pendingUserProperties?.let { doUpdateUserProperties(it) }
@@ -159,6 +164,7 @@ class DefaultVectorAnalytics @Inject constructor(
                     // When opting out, ensure that the queue is flushed first, or it will be flushed later (after user has revoked consent)
                     posthog?.flush()
                     posthog?.optOut(true)
+                    posthog = null
                 }
             }
         }