Remove Unsupported JDKs

The JDKs 9 and 10 are no longer supported by Oracle and the
CAs are not up to date, so removing from the build.

18:13:02  * What went wrong:
18:13:02  Execution failed for task ':buildSrc:compileJava'.
18:13:02  > Could not resolve all files for configuration ':buildSrc:compileClasspath'.
18:13:02     > Could not resolve com.thaiopensource:trang:20091111.
18:13:02       Required by:
18:13:02           project :buildSrc
18:13:02        > Could not resolve com.thaiopensource:trang:20091111.
18:13:02           > Could not get resource 'https://repo.maven.apache.org/maven2/com/thaiopensource/trang/20091111/trang-20091111.pom'.
18:13:02              > Could not GET 'https://repo.maven.apache.org/maven2/com/thaiopensource/trang/20091111/trang-20091111.pom'.
18:13:02                 > sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
18:13:02     > Could not resolve net.sourceforge.saxon:saxon:9.1.0.8.
18:13:02       Required by:
18:13:02           project :buildSrc
18:13:02        > Could not resolve net.sourceforge.saxon:saxon:9.1.0.8.
18:13:02           > Could not get resource 'https://repo.maven.apache.org/maven2/net/sourceforge/saxon/saxon/9.1.0.8/saxon-9.1.0.8.pom'.
18:13:02              > Could not GET 'https://repo.maven.apache.org/maven2/net/sourceforge/saxon/saxon/9.1.0.8/saxon-9.1.0.8.pom'.
18:13:02                 > sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to request

Jenkinsfile

@@ -74,42 +74,6 @@ try {
 			}
 		}
 	},
-	jdk9: {
-		stage('JDK 9') {
-			node {
-				checkout scm
-				sh "git clean -dfx"
-				try {
-					withCredentials([ARTIFACTORY_CREDENTIALS]) {
-						withEnv(["JAVA_HOME=${ tool 'jdk9' }"]) {
-							sh "./gradlew $JENKINS_USER clean test -PartifactoryUsername=$ARTIFACTORY_USERNAME -PartifactoryPassword=$ARTIFACTORY_PASSWORD --refresh-dependencies --no-daemon --stacktrace"
-						}
-					}
-				} catch(Exception e) {
-					currentBuild.result = 'FAILED: jdk9'
-					throw e
-				}
-			}
-		}
-	},
-	jdk10: {
-		stage('JDK 10') {
-			node {
-				checkout scm
-				sh "git clean -dfx"
-				try {
-					withCredentials([ARTIFACTORY_CREDENTIALS]) {
-						withEnv(["JAVA_HOME=${ tool 'jdk10' }"]) {
-							sh "./gradlew $JENKINS_USER clean test -PartifactoryUsername=$ARTIFACTORY_USERNAME -PartifactoryPassword=$ARTIFACTORY_PASSWORD --refresh-dependencies --no-daemon --stacktrace"
-						}
-					}
-				} catch(Exception e) {
-					currentBuild.result = 'FAILED: jdk10'
-					throw e
-				}
-			}
-		}
-	},
 	jdk11: {
 		stage('JDK 11') {
 			node {