Handle codec negotiation failed.

If the codec negotiation fails, we never reset current scb
which results in stack being in BTA_AG_SCO_LISTEN_ST and
new connections transfered instead of opened.
As transfers are ignored in listen state, no sco could be
opened until the first device failing negotiation was
disconnected.

Handling the BTA_AG_SCO_CLOSE_E (result of a negotiation
failed) in order to remove the current scb and let other
devices open sco.

There are no current tests for the SCO state machine, so
keeping this change behind a flag until then.

Bug: 265582589
Tag: #feature
Test: Manual, forced codec nego timeout. Behind a flag.
Change-Id: Ic73cc0d44a5d966e4353012f170d5a664799074c