Old (closed) private tabs are reopening after V1.7 upgrade

[anthonypkeane]

Description:

Since upgrading to V1.7, some users are reporting that their old private tabs are reopening.

Steps to Reproduce (difficult to reproduce)

1. Have an old install of Brave V1.x installed on an iOS device
2. Create some private tabs, and close them
3. Upgrade to V1.7

Actual result:
as above

Expected result:
V1.7 should upgrade as normal, private tabs should not be re opened

Reproduces how often:
Hard to say, users are reporting it since the upgrade to V1.7

Brave Version:
V1.7

Device details:
We need user input here and have requested it via the various support channels