Improve BT ICS binding/unbinding timing.

Separately bind and unbind bluetooth InCallService to improve call audio
via bluetooth devices.

Bug: b/306395598
Test: CallsManagerTest, InCallControllerTest
Change-Id: I68ee98eed46fccbb8b8d4674a0d8d44bc8dd1122
diff --git a/flags/telecom_incallservice_flags.aconfig b/flags/telecom_incallservice_flags.aconfig
index e1a652b..1110ca4 100644
--- a/flags/telecom_incallservice_flags.aconfig
+++ b/flags/telecom_incallservice_flags.aconfig
@@ -12,4 +12,11 @@
   namespace: "telecom"
   description: "Ensure that users are able to return to call from keyguard UI for ECC"
   bug: "306582821"
-}
\ No newline at end of file
+}
+
+flag {
+  name: "separately_bind_to_bt_incall_service"
+  namespace: "telecom"
+  description: "Binding/Unbinding to BluetoothInCallServices in proper time to improve call audio"
+  bug: "306395598"
+}