Add feature flag to support SIP subscribe retry

Bug: 323278352
Test: build pass
Change-Id: Ie1fde6e8c32c39f85f8d563951a6a49b9ec94d4b
diff --git a/flags/ims.aconfig b/flags/ims.aconfig
index d09259e..b2cc904 100644
--- a/flags/ims.aconfig
+++ b/flags/ims.aconfig
@@ -62,3 +62,10 @@
     description: "This flag updates roaming state to set wfc mode"
     bug:"317298331"
 }
+
+flag {
+    name: "enable_sip_subscribe_retry"
+    namespace: "telephony"
+    description: "This flag controls whether framework supports SIP subscribe retry or not"
+    bug:"297023230"
+}