chore(flux): update image docker.io/rancher/system-upgrade-controller v0.15.2 → v0.15.3 (clustertool) (#36822)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
|
[docker.io/rancher/system-upgrade-controller](https://redirect.github.com/rancher/system-upgrade-controller)
| patch | `v0.15.2` -> `v0.15.3` |

---

> [!WARNING]
> Some dependencies could not be looked up. Check the Dependency
Dashboard for more information.

---

### Release Notes

<details>
<summary>rancher/system-upgrade-controller
(docker.io/rancher/system-upgrade-controller)</summary>

###
[`v0.15.3`](https://redirect.github.com/rancher/system-upgrade-controller/releases/tag/v0.15.3)

[Compare
Source](https://redirect.github.com/rancher/system-upgrade-controller/compare/v0.15.2...v0.15.3)

#### What's Changed

- Fix securityContext and volumes for prepare by
[@&#8203;maltelehmann](https://redirect.github.com/maltelehmann) in
[https://github.com/rancher/system-upgrade-controller/pull/364](https://redirect.github.com/rancher/system-upgrade-controller/pull/364)
- Bump golang.org/x/crypto from 0.28.0 to 0.35.0 by
[@&#8203;dependabot](https://redirect.github.com/dependabot) in
[https://github.com/rancher/system-upgrade-controller/pull/362](https://redirect.github.com/rancher/system-upgrade-controller/pull/362)
- Rework Plan CRD generation to add docs and `kubectl explain` support
by [@&#8203;brandond](https://redirect.github.com/brandond) in
[https://github.com/rancher/system-upgrade-controller/pull/369](https://redirect.github.com/rancher/system-upgrade-controller/pull/369)

#### New Contributors

- [@&#8203;maltelehmann](https://redirect.github.com/maltelehmann) made
their first contribution in
[https://github.com/rancher/system-upgrade-controller/pull/364](https://redirect.github.com/rancher/system-upgrade-controller/pull/364)

**Full Changelog**:
https://github.com/rancher/system-upgrade-controller/compare/v0.15.2...v0.15.3

</details>

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clustertool/embed/generic/kubernetes/system/system-upgrade-controller/app/helm-release.yaml

@@ -33,7 +33,7 @@ spec:
           app:
             image:
               repository: docker.io/rancher/system-upgrade-controller
-              tag: v0.15.2@sha256:3e899833afcea9a8788d384ce976df9a05be84636fe5c01ec2307b5bd8fe9810
+              tag: v0.15.3@sha256:b8f3ae8be508b6c80340bf9e3733332ecdaddd80dc573626a42a62e30e6a51bb
             env:
               SYSTEM_UPGRADE_CONTROLLER_DEBUG: false
               SYSTEM_UPGRADE_CONTROLLER_THREADS: 2