cquery: make it easier to source Starlark transitions

**Before:**

```
$ bazel cquery --transitions=lite <query with a target with a self (rule) transition>
FunctionPatchTransition -> //the:target (abcd1)
```

**After:**

```
$ bazel cquery --transitions=lite <query with a target with a self (rule) transition>`
Starlark transition:foo/bar/transition_def.bzl:21:32 -> //the:target (abcd1)
```

**Implementation notes:**
- This is a no-op for native transitions: https://github.com/bazelbuild/bazel/blob/a9206ebe275ce3de22f5c68b03ad58f6ae0b0cb2/src/main/java/com/google/devtools/build/lib/analysis/config/transitions/ConfigurationTransition.java#L96
- StarlarkTransition.getName() already has the most helpful form: https://github.com/bazelbuild/bazel/blob/a9206ebe275ce3de22f5c68b03ad58f6ae0b0cb2/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkTransition.java#L72
- This only updates rule transitions (rules that self-transition). Attribute transitions (transitions applied to rule attributes) already have this behavior: https://github.com/bazelbuild/bazel/blob/1661a9c3128dca895f4853c8c8d022902bf90d7e/src/main/java/com/google/devtools/build/lib/query2/cquery/TransitionsOutputFormatterCallback.java#L172

PiperOrigin-RevId: 422373835

Author: gregestren

src/main/java/com/google/devtools/build/lib/query2/cquery/TransitionsOutputFormatterCallback.java

@@ -202,8 +202,7 @@ private static String getRuleClassTransition(ConfiguredTarget ct, Target target)
         output =
             factory
                 .create(RuleTransitionData.create(target.getAssociatedRule()))
-                .getClass()
-                .getSimpleName()
+                .getName()
                 .concat(" -> ");
       }
     }