docs: document that policyMapMax overrides dynamic policy map size
docs: document that policyMapMax overrides dynamic policy map size

The policyMapMax helm option was introduced after the
mapDynamicSizeRatio option in #11478. Thus, the fact that explicitly
specifying the maximum disables the dynamic sizing of the policy map was
not mentioned in the upgrade guide. Document this now.

While at it, also fix the name of the helm option for the dynamic sizing
in the upgrade guide. It was using the command line option name, not the
helm option name.

Signed-off-by: Tobias Klauser <9249c549618448e4c699e8032ba6c7f0d7fd4b7f@distanz.ch>

cilium-team/cilium,michi-covalent/cilium,michi-covalent/cilium,michi-covalent/cilium,michi-covalent/cilium,cilium/cilium,tklauser/cilium,tklauser/cilium,tklauser/cilium,cilium/cilium,tgraf/cilium,cilium/cilium,tgraf/cilium,michi-covalent/cilium,tgraf/cilium,cilium/cilium,tgraf/cilium,tklauser/cilium,cilium-team/cilium,tgraf/cilium,cilium/cilium,tgraf/cilium,tklauser/cilium