Disable adjust_by_ram for swap at TW since it is not fully implemented (

#1097)

## Problem

As part of #1081, we enabled at the Tumbleweed configuration the
parameter `adjust_by_ram` for the outline of the swap volume.

But the feature is not really implemented yet because we have not
defined all the details of how we want it to work and how distribute the
logic between Agama itself and yast2-storage-ng (more details at this
[non-public Trello
card](https://trello.com/c/cki2gJ3b/366-agama-dynamic-sizes-based-on-ram)).
`AdjustByRam` was added to the definition of the outlines only as a
preliminary step, but we never went further and at this point in time
the user cannot actually adjust the size if "auto" is not wanted.

## Solution

Revert commit 9f537c6 until we
implement the feature in a more final (at least complete) way.

products.d/tumbleweed.yaml

@@ -165,12 +165,10 @@ storage:
     - mount_path: "swap"
       filesystem: swap
       size:
-        auto: true
+        auto: false
+        min: 1 GiB
+        max: 2 GiB
       outline:
-        auto_size:
-          base_min: 1 GiB
-          base_max: 2 GiB
-          adjust_by_ram: true
         required: false
         filesystems:
           - swap