Fix Java coverage collection with Java 8 runtime

`JacocoCoverageRunner` is run with the target runtime, not the exec runtime, and thus needs to be compatible with a Java 8 runtime.

Fixes bazelbuild#17165

Closes bazelbuild#17338.

PiperOrigin-RevId: 509123073
Change-Id: I41d7255e1f3c3dd3864082899d5dc9ab2cc82027

Author: fmeum

src/java_tools/junitrunner/java/com/google/testing/coverage/JacocoLCOVFormatter.java

@@ -70,7 +70,7 @@ public IReportVisitor createVisitor(
       private Map<String, ISourceFileCoverage> sourceToFileCoverage = new TreeMap<>();
 
       private String getExecPathForEntryName(String classPath) {
-        if (execPathsOfUninstrumentedFiles.isEmpty()) {
+        if (!execPathsOfUninstrumentedFiles.isPresent()) {
           return classPath;
         }
 

src/main/java/com/google/devtools/build/lib/rules/java/JavaToolchainRule.java

@@ -281,8 +281,6 @@ The Java target version (e.g., '6' or '7'). It specifies for which Java runtime
         <!-- #END_BLAZE_RULE.ATTRIBUTE --> */
         .add(
             attr("jacocorunner", LABEL)
-                // This needs to be in the execution configuration.
-                .cfg(ExecutionTransitionFactory.create())
                 .allowedFileTypes(FileTypeSet.ANY_FILE)
                 .exec())
         /* <!-- #BLAZE_RULE(java_toolchain).ATTRIBUTE(proguard_allowlister) -->