Revert "Floss: Disconnect device after GATT client closes"

This reverts commit 4a6b6241.

Reason for revert: b/361430492 - breaking CTSV
Bug: 361430492
Test: m com.android.btservices
Test: manual
Flag: Exempt, Floss-only

Change-Id: Iff409e7d71a7fdb7824b14fdc725f1f53367ee5d