Correctly disable UDS_ACCESS being set

Summary:
718abcb6 tries to disable UDS_ACCESS
being set. See the long comment introduced.

It did this by setting the value to -1 which doesn't achieve that
result.

-1 is a perfectly valid value that gets send to the client.

Having it set breaks anyone calling udsEntry.numberValue(UDS_ACCESS,
aLegitimateDefault) getting their default. Something used by kio-fuse.

Test Plan:
Used kio-fuse
Opened a samba file in mplayer
It opened

Opened a text editor in kate (using regular kio)

Reviewers: sitter, feverfew

Reviewed By: sitter

Subscribers: kde-frameworks-devel, kfm-devel

Tags: #dolphin, #frameworks

Differential Revision: https://phabricator.kde.org/D27810