Remove references to Rancher chart rename

[btat]

The Rancher chart was temporarily renamed during v2.13.1 and reverted in v2.13.2. This change is not relevant beyond that period so the references can be removed.

Related:

• Revert chart name change introduced in Rancher Prime v2.13.1 #684
• Update chart name for Rancher v2.13.1 #624