Add host transition to lcov_merger in Java version of py_test

Fixes bazelbuild#17568

Closes bazelbuild#17587.

PiperOrigin-RevId: 512563828
Change-Id: If95b26f5b86b2848dbaaf6129d1daa1538a22826

src/main/java/com/google/devtools/build/lib/bazel/rules/python/BazelPyTestRule.java

@@ -57,7 +57,10 @@ public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment env)
             attr("$launcher", LABEL)
                 .cfg(ExecutionTransitionFactory.create())
                 .value(env.getToolsLabel("//tools/launcher:launcher")))
-        .add(attr(":lcov_merger", LABEL).value(BaseRuleClasses.getCoverageOutputGeneratorLabel()))
+        .add(
+            attr(":lcov_merger", LABEL)
+                .cfg(ExecutionTransitionFactory.create())
+                .value(BaseRuleClasses.getCoverageOutputGeneratorLabel()))
         // Add the script as an attribute in order for py_test to output code coverage results for
         // code covered by CC binaries invocations.
         .add(