Backport #95101 (arch: arm: switch to privilege stack in SVC handler)

### Describe the bug

This is to make sure #95101 is backported to all supported Zephyr versions.

### Regression

- [ ] This is a regression.

### Steps to reproduce

_No response_

### Relevant log output

```shell

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### Impact

Not sure

### Environment

_No response_

### Additional Context

_No response_