ui: node status: increase warning/critical threshold percentage for memory usage

Memory is there to be used and unlike with block/file storage it can
be fine, even wanted to use all memory besides a bit of headroom.
As memory is easy to defragment (it's all virtual addresses anyway)
and some usage is also easy to evict (e.g. to SWAP if not really used
at the moment or as it is only an advanced cache like the ZFS ARC).

Without the override the threshold where 75% for warning and 90% for
showing a critical status. For a host with 396 GiB of installed memory
that meant that we warned already on 297 GiB used (99 GiB still
available!) and showed a critical status with ~365 GiB in use (~40 GiB
free), both can be still very OK and warranted usages though.

So increase the thresholds to 90% for warning and 97.5% for critical
usage displays, which provides a less "scare-mongering" display.

Ideally we'd support a callback to make a better decision, as clamping
on totals might be even better, but this simple change makes it
already much better. Add a comment that we might want to split out the
ARC in its own custom bar (I got a prototype around, but that needs
polishing and in-depth review).

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

www/manager6/node/StatusView.js

@@ -54,6 +54,9 @@ Ext.define('PVE.node.StatusView', {
             title: gettext('RAM usage'),
             valueField: 'memory',
             maxField: 'memory',
+            warningThreshold: 0.9,
+            criticalThreshold: 0.975,
+            // TODO: split out ARC usage
             renderer: Proxmox.Utils.render_node_size_usage,
         },
         {