Incorrect `PathExpression` Passed into Plan Modifier of an Attribute in a 2nd Layer Nested Object

### Module version

```
github.com/hashicorp/terraform-plugin-framework v1.15.1
```

### Relevant provider source code
```go
package nestedsettest

import (
"context"
"fmt"

"github.com/hashicorp/terraform-plugin-framework/resource"
"github.com/hashicorp/terraform-plugin-framework/resource/schema"
"github.com/hashicorp/terraform-plugin-framework/resource/schema/planmodifier"
)

// UseStateForUnknownIf returns a plan modifier that will only use the state value
// in place of an unknown value if the given condition is met.
func SampleModifier() planmodifier.String {
return sampleModifier{}
}

type sampleModifier struct {
}

func (m sampleModifier) Description(_ context.Context) string {
return "Once set, the value of this attribute in state will not change " +
"if the given condition is met."
}

func (m sampleModifier) MarkdownDescription(_ context.Context) string {
return "Once set, the value of this attribute in state will not change " +
"if the given condition is met."
}

func (m sampleModifier) PlanModifyString(
ctx context.Context,
req planmodifier.StringRequest,
resp *planmodifier.StringResponse,
) {
panic(fmt.Sprintf("%v", req.PathExpression))
}

func NewResource() resource.Resource {
return &setNestedExampleResource{}
}

type setNestedExampleResource struct{}

func (r *setNestedExampleResource) Metadata(
ctx context.Context,
req resource.MetadataRequest,
resp *resource.MetadataResponse,
) {
resp.TypeName = "linode_nested_attrs_resource"
}

func (r *setNestedExampleResource) Schema(ctx context.Context, req resource.SchemaRequest, resp *resource.SchemaResponse) {
resp.Schema = schema.Schema{
Attributes: map[string]schema.Attribute{
"nested": schema.SingleNestedAttribute{
Optional: true,
Computed: true,
Attributes: map[string]schema.Attribute{
"double_nested": schema.SingleNestedAttribute{
Optional: true,
Computed: true,
Attributes: map[string]schema.Attribute{
"str_a": schema.StringAttribute{
Computed: true,
Optional: true,
PlanModifiers: []planmodifier.String{
SampleModifier(),
},
},
},
},
},
},
},
}
}

func (r *setNestedExampleResource) Create(ctx context.Context, req resource.CreateRequest, resp *resource.CreateResponse) {
resp.State.Raw = req.Plan.Raw
}

func (r *setNestedExampleResource) Read(ctx context.Context, req resource.ReadRequest, resp *resource.ReadResponse) {
resp.State.Raw = req.State.Raw
}

func (r *setNestedExampleResource) Update(ctx context.Context, req resource.UpdateRequest, resp *resource.UpdateResponse) {
resp.State.Raw = req.Plan.Raw
}

func (r *setNestedExampleResource) Delete(ctx context.Context, req resource.DeleteRequest, resp *resource.DeleteResponse) {
}

```

### Terraform Configuration Files
```hcl
resource "linode_nested_attrs_resource" "test" {
nested = {
double_nested = {

}
}
}
```

### Expected Behavior
The correct path to reach the attribute from root is: `nested.double_nested.str_a`

### Actual Behavior
The output path from the panic message is: `double_nested.str_a`