Show -Dlicense.key value in test repro info (elastic#66179)

- When a -Dlicense.key sys property is passed to the build we want to consider
this in the test reproduction info message
- Absolute Paths tried to be converted to relative paths relative to workspace
root to allow simply copy & paste
- Also fixes a inconsistency for checking license existence in x-pack plugin core build

test/framework/src/main/java/org/elasticsearch/test/junit/listeners/ReproduceInfoPrinter.java

@@ -79,7 +79,6 @@ public void testFailure(Failure failure) throws Exception {
         String task = System.getProperty("tests.task");
         // TODO: enforce (intellij still runs the runner?) or use default "test" but that won't work for integ
         b.append("'" + task + "'");
-
         GradleMessageBuilder gradleMessageBuilder = new GradleMessageBuilder(b);
         gradleMessageBuilder.appendAllOpts(failure.getDescription());
 
@@ -159,6 +158,7 @@ public ReproduceErrorMessageBuilder appendESProperties() {
             appendOpt("tests.distribution", System.getProperty("tests.distribution"));
             appendOpt("compiler.java", System.getProperty("compiler.java"));
             appendOpt("runtime.java", System.getProperty("runtime.java"));
+	    appendOpt("license.key", System.getProperty("licence.key"));
             appendOpt("javax.net.ssl.keyStorePassword", System.getProperty("javax.net.ssl.keyStorePassword"));
             appendOpt("javax.net.ssl.trustStorePassword", System.getProperty("javax.net.ssl.trustStorePassword"));
             return this;

x-pack/plugin/core/build.gradle

@@ -69,10 +69,11 @@ processResources {
   } else {
     throw new IllegalArgumentException('Property license.key must be set for release build')
   }
-  if (Files.exists(Paths.get(licenseKey)) == false) {
+  File licenseKeyFile = rootProject.file(licenseKey)
+  if (licenseKeyFile.exists() == false) {
     throw new IllegalArgumentException('license.key at specified path [' + licenseKey + '] does not exist')
   }
-  from(licenseKey) {
+  from(licenseKeyFile) {
     rename { String filename -> 'public.key' }
   }
 }