Revert "[cobalt-fidl] Remove [Transitional] tag"

This reverts commit da1e19bd2a36ac762562e0bd6fe68e353919f0a9.

Reason for revert: This causes build errors, not sure how it got through CQ.

Original change's description:
> [cobalt-fidl] Remove [Transitional] tag
>
> do not submit until change lands in garnet
>
> Change-Id: I420b6c594f044c736ab1eccc12267b2eec8933d4

TBR=rudominer@google.com,zmbush@google.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Change-Id: Icc207994f8a469523128cb92e46e8a96024a9008
diff --git a/sdk/fidl/fuchsia.cobalt/fuchsia.cobalt.api b/sdk/fidl/fuchsia.cobalt/fuchsia.cobalt.api
index 89c0c29..4799ba0 100644
--- a/sdk/fidl/fuchsia.cobalt/fuchsia.cobalt.api
+++ b/sdk/fidl/fuchsia.cobalt/fuchsia.cobalt.api
@@ -1,4 +1,4 @@
 {
-  "fidl/fuchsia.cobalt/cobalt.fidl": "89cd0201c801cc0f055ceebc04025c75",
+  "fidl/fuchsia.cobalt/cobalt.fidl": "33243c7e399f211b8930c2d2a45a637f",
   "fidl/fuchsia.cobalt/cobalt_controller.fidl": "82a15c5eecd9d53292c8bc759e7ac389"
 }
\ No newline at end of file
diff --git a/zircon/system/fidl/fuchsia-cobalt/cobalt.fidl b/zircon/system/fidl/fuchsia-cobalt/cobalt.fidl
index 74fb351..adf6b99 100644
--- a/zircon/system/fidl/fuchsia-cobalt/cobalt.fidl
+++ b/zircon/system/fidl/fuchsia-cobalt/cobalt.fidl
@@ -590,11 +590,13 @@
     // methods defined above. The reason to use this method is that a
     // CobaltEvent allows multiple event codes to be specified whereas the
     // methods above allow only a single event code.
+    [Transitional]
     LogCobaltEvent(CobaltEvent event) -> (Status status);
 
     // Logs a list of CobaltEvents. This method is equivalent to invoking
     // LogCobaltEvent() multiple times but is more efficient as it requires only
     // a single FIDL call.
+    [Transitional]
     LogCobaltEvents(vector<CobaltEvent> events) -> (Status status);
 };