olm try to decrypt with recent session first

changelog.d/5872.misc

@@ -0,0 +1 @@
+Faster Olm decrypt when there is a lot of existing sessions

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/OlmSessionStore.kt

@@ -66,7 +66,8 @@ internal class OlmSessionStore @Inject constructor(private val store: IMXCryptoS
         olmSessions.getOrPut(deviceKey) { mutableListOf() }.forEach { cached ->
             getSafeSessionIdentifier(cached.olmSession)?.let { cachedSessionId ->
                 if (!persistedKnownSessions.contains(cachedSessionId)) {
-                    persistedKnownSessions.add(cachedSessionId)
+                    // as it's in cache put in on top
+                    persistedKnownSessions.add(0, cachedSessionId)
                 }
             }
         }

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/store/db/RealmCryptoStore.kt

@@ -715,6 +715,7 @@ internal class RealmCryptoStore @Inject constructor(
         return doWithRealm(realmConfiguration) {
             it.where<OlmSessionEntity>()
                     .equalTo(OlmSessionEntityFields.DEVICE_KEY, deviceKey)
+                    .sort(OlmSessionEntityFields.LAST_RECEIVED_MESSAGE_TS, Sort.DESCENDING)
                     .findAll()
                     .mapNotNull { sessionEntity ->
                         sessionEntity.sessionId