Move getLastKnownCellIdentity to its own flag.

Moving this API to a different flag so that it won't block 24Q3; it will
launch is 25Q3.

Test: This API has a CTS test.
Bug: 327454165
Change-Id: I9889da2e5a5d9f49db07f438dd4c122b18031865
diff --git a/flags/telecom_api_flags.aconfig b/flags/telecom_api_flags.aconfig
index c44bea4..8e1ab52 100644
--- a/flags/telecom_api_flags.aconfig
+++ b/flags/telecom_api_flags.aconfig
@@ -49,3 +49,10 @@
   description: "Enables enriched calling features (e.g. Business name will show for a call)"
   bug: "311688497"
 }
+
+flag{
+  name: "get_last_known_cell_identity"
+  namespace: "telecom"
+  description: "Formalizes the getLastKnownCellIdentity API that Telecom reliees on as a system api"
+  bug: "327454165"
+}