go_test: could not use x_defs to stamp rlocationpath of another binary in data

### What version of rules_go are you using?

0.44.2

### What version of gazelle are you using?

0.35.0

### What version of Bazel are you using?

7.0.2

### Does this issue reproduce with the latest releases of all the above?

yes

### What operating system and processor architecture are you using?

MacOS ARM64

### Any other potentially useful information about your toolchain?

Irrelevant

### What did you do?

Here is a minimal reproduce
https://github.com/sluongng/rules-go-test-xdefs-issue/blob/9360ec82c4f307d0e986f36580b2b90cb6760f1c/BUILD#L10-L12

### What did you expect to see?

The x_defs should detect the runfile locations of the target and add it to the Go variable

### What did you see instead?

```
ERROR: /Users/sluongng/work/misc/test-go/BUILD:6:8: in go_test rule //:a_test: label '//liba:liba' in $(location) expression is not a declared prerequisite of this rule
ERROR: /Users/sluongng/work/misc/test-go/BUILD:6:8: Analysis of target '//:a_test' failed
```

Start with the minimal reproduction linked in the issue, especially the BUILD file at lines 10–12, and reproduce the go_test analysis error with x_defs and the binary in data. Trace how go_test handles $(location) and runfile locations for x_defs; done means the target’s rlocationpath can be stamped without the declared-prerequisite error.

Written by the indexing model from the issue text.