gatt: Add missing disconnect call to EATT layer

When remote device disconnected the link, usually l2cap calls disconnect
callbacks which clears eatt channels. However sometimes Eatt might not
get it first and later could be asked to provide queued commands  -
which should be not there when link disconnected.

Bug: 249431973
Test: atest BluetoothInstrumentationTests
Test: disconnect while discovering during bonding
Tag: #feature

Change-Id: I5fa2370dfefaf36646cb61e128c966e9343eeb55