Open connection if it doesn't exsist in bta_gattc_process_indicate

If Service Changed indication is received before the connection is open
, send the BTA_GATTC_INT_CONN_EVT to open it before processing the
indication.

Bug: 131814072
Test: CTS Bluetooth LE Secure Test. Unit test.

Change-Id: I1b3415ef6aafb52a6ac229409514a85f35de5842
Merged-In: I1b3415ef6aafb52a6ac229409514a85f35de5842