[BUG] In Inhibit rules, Target Labels cannot be assigned labels with the same name but different values.

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Current Behavior

I tried to assign two labels with same name but different values in the target labels, but the system only retained the last value entered.

### Expected Behavior

_No response_

### Steps To Reproduce

_No response_

### Environment

```markdown
HertzBeat version(s):v1.7.2
```

### Debug logs

_No response_

### Anything else?

_No response_

The issue names no source files, tests, or entry points. Start by locating the Inhibit rules target-label handling in the HertzBeat codebase and reproduce the case with two labels sharing a name but having different values. Done means both label values are retained, with regression coverage for the reported behavior.

Written by the indexing model from the issue text.