Begin using `rancher/kuberlr-kubectl` instead of `rancher/kubectl`

[mallardduck]

fleet/charts/fleet-agent/values.yaml

Lines 69 to 71 in 71eed6b

	kubectl:
	repository: rancher/kubectl
	tag: v1.31.7

Per the title, this issue is to inform the Fleet team that O&B team is rolling out our new rancher/kuberlr-kubectl which will replace rancher/kubectl. This change brings improvements to k8s compatibility ranges - particularly within airgaps - for our charts that need access to kubectl binary.

Here are some helpful directions on how to update charts for this and what tags to target per branch.

Cheatsheet: Rancher Branches Kubectl -> Kuberlr Tag

Rancher Tag (Branch)	rancher/kubectl tag	rancher/kuberlr-kubectl tag
2.11.Z (main)	*	v4.0.2
2.10.Z (release/v2.10)	*	v3.0.1

1. Find: rancher/kubectl replace with: rancher/kuberlr-kubectl,
2. Identify Rancher Branch your current repo branch targets to pick tag,
3. Find all old tags of kubectl and update to tag identified in step 2,
4. Repeat 1-3 for each active branch of project.

Our team (O&B) has already adopted this for the charts and projects we maintain.
Please do not hesitate to reach out with any questions or concerns.

P.s. Technically there is a branch for 2.9 that we will be maintaining, however as 2.9 is EoM already it's fine to exclude that branch from adoption. The primary target is to ensure that 2.10+ will be using the new kuberlr based images.