Enable unassigned items banner for self-host (#3978)

src/Api/Vault/Controllers/CiphersController.cs

@@ -1118,11 +1118,10 @@ public class CiphersController : Controller
     [HttpGet("has-unassigned-ciphers")]
     public async Task<bool> HasUnassignedCiphers()
     {
-        var orgAbilities = await _applicationCacheService.GetOrganizationAbilitiesAsync();
-
+        // We don't filter for organization.FlexibleCollections here, it's shown for all orgs, and the client determines
+        // whether the message is shown in future tense (not yet migrated) or present tense (already migrated)
         var adminOrganizations = _currentContext.Organizations
-            .Where(o => o.Type is OrganizationUserType.Admin or OrganizationUserType.Owner &&
-                        orgAbilities.ContainsKey(o.Id) && orgAbilities[o.Id].FlexibleCollections);
+            .Where(o => o.Type is OrganizationUserType.Admin or OrganizationUserType.Owner);
 
         foreach (var org in adminOrganizations)
         {

src/Core/Constants.cs

@@ -149,7 +149,8 @@ public static class FeatureFlagKeys
         {
             { TrustedDeviceEncryption, "true" },
             { Fido2VaultCredentials, "true" },
-            { DuoRedirect, "true" }
+            { DuoRedirect, "true" },
+            { UnassignedItemsBanner, "true"}
         };
     }
 }