fetch answers: rename partition search label

fetch answers: rename partition search label

The new one is far from perfect either, but labels can be at max 16
characters, so that's what we have to work with.

It now is slightly easier to read due to the hyphen separation and
contains the following relevant info:
- proxmox spelled out in full, so anybody seeing that label has a good
  chance to narrow down what it could do already by a lot
- inst is a bit cryptic, but that Proxmox has a installer is a easy to
  find out fact
- src should hopefully relay that this is the source of
  (configuration) for something related to a installer by proxmox

But yeah, please don't limit IDs or names to less than 32, ideally
even 64, characters, that's the bare minimum to get some expressive
names that can have actual meaning..

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