Revert "HADOOP-19298. [JDK17] Add a JDK17 profile. (#7085) Contributed by Shilun Fan." (#7132)

This reverts commit f931ede86b635b1a92d6208138c2c6692ed616bc.

hadoop-project/pom.xml

@@ -2754,16 +2754,6 @@
         </dependencies>
       </dependencyManagement>
     </profile>
-    <!-- We added this profile to support compilation for JDK 9 and above. -->
-    <profile>
-      <id>java9</id>
-      <activation>
-        <jdk>[9,)</jdk>
-      </activation>
-      <properties>
-        <maven.compiler.release>${javac.version}</maven.compiler.release>
-      </properties>
-    </profile>
   </profiles>
 
   <repositories>