Automatic merge from submit-queue (batch tested with PRs 57550, 60089). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Remove subnet size restriction for IPv6

RangeSize was restricting IPv6 subnets to a /66 due to the
logic using a uint64. This is not practical for IPv6.
This change removes the /64 restriction, but also sets a limit
on the range that can be allocated, so that the bitmap will not grow too large.

**What this PR does / why we need it**:
This PR removes the /66 restriction in ipallocator for IPv6. It is not practical to restrict
IPv6 to /66. Currently a /64 or /48 is not allowed. The problem with removing the restriction is
the bitmap that tracks the subnets can grow really large, so a  limit
on the max size of the subnet was set to 65536. 
Setting the max size will have a side-effect with larger subnets that the allocator
will allocate in a smaller section of IP's, this will need to be addressed in a follow-on PR.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #60081

**Special notes for your reviewer**:

**Release note**:

```release-note-none
```