gatt: Fix incorrect GATT confirmation on indication

If there is many GATT users, Android sends indication to all the users
and expects confimation.
Without this fix, we could endup sending multiple Confirmation to remote
device on single Indication - which is wrong.

This patch fixes this.
Found during PTS HAP testing.

Bug: 238171211
Test: atest BluetoothInstrumentationTests
Test: PTS
tag: #feature
Merged-In: Ieef9a0f3448ce8529624e777282e857a7f206c00
Change-Id: Ieef9a0f3448ce8529624e777282e857a7f206c00
(cherry picked from commit 090653c2)