Reapply "[clang] Remove intrusive reference count from `DiagnosticOptions` (#139584)"

This reverts commit e2a885537f11f8d9ced1c80c2c90069ab5adeb1d. Build failures were fixed right away and reverting the original commit without the fixes breaks the build again.

NOKEYCHECK=True
GitOrigin-RevId: 13e1a2cb2246dc5e9a4afcdacabed4d43154ec3f
1 file changed