mgr/dashboard: fix the landing page layout issues

mgr/dashboard: fix the landing page layout issues

We were following a row-col grid layout for the landing page.
First row includes Details, Status and Capacity
Second row for Inventory and Cluster Utilization

So if one of the item in the first row increases, it pushes the entire
second row downwards.

To fix this, I made a col-row grid.

First col has Details and Inventory in two rows.
Second col has Status and Capacity as a col and Cluster Utilization as a
single row

Fixes: https://tracker.ceph.com/issues/62961
Signed-off-by: Nizamudeen A <nia@redhat.com>
Co-authored-by: cloudbehl <cloudbehl@gmail.com>