Tag the build scan with the JDK that was used

Closes gh-19615

gradle/build-scan-user-data.gradle

@@ -1,4 +1,5 @@
 tagOs()
+tagJdk()
 tagIde()
 tagCiOrLocal()
 addGitMetadata()
@@ -7,6 +8,10 @@ void tagOs() {
 	gradleEnterprise.buildScan.tag System.getProperty('os.name')
 }
 
+void tagJdk() {
+	gradleEnterprise.buildScan.tag "JDK-${System.getProperty('java.specification.version')}"
+}
+
 void tagIde() {
 	if (System.getProperty('idea.version')) {
 		gradleEnterprise.buildScan.tag 'IntelliJ IDEA'