Superfluous value copies inside plugin options

### Expected behavior

Options set for a plugin should be received as they are by the plugin.

### Current behavior

When the plugin options value has a given structure (e.g. a property contains an array of objects), some values seem to be copied from the options itself into its parts.

In the example that I provide, the passed options value is:

```js
{
some_array_of_objects: [{ prop: 1 }, { prop: 2 }]
}
```

But the received value in the plugin lifecycle callbacks is:

```js
{
"some_array_of_objects": [
{
"prop": 1,
"0": {
"prop": 1
},
"1": {
"prop": 2
}
},
{
"prop": 2,
"0": {
"prop": 1
},
"1": {
"prop": 2
}
}
]
}
```

### Reproducible sample

https://codepen.io/aeqz/pen/rNQRgaw

### Optional extra steps/info to reproduce

_No response_

### Possible solution

_No response_

### Context

I noticed that my site performance was degrading exponentially with each interaction with a chart that used a custom plugin.

One of the plugin options, which consisted of an array of ranges selected by the user, was being sent back through a callback when the user interacted with the chart in order to modify its selection, and received again as an options value, which is how usually input elements work in React. Due to the behaviour that I'm reporting, this interaction cycle was producing an exponential growth of undesired copied data within the options value.

### chart.js version

v4.3.3

### Browser name and version

_No response_

### Link to your project

_No response_