YARN-11053. AuxService should not use class name as default system classes

[pan3793]

Description of PR

[YARN-11053] AuxService should not use class name as default system classes

Currently, if yarn.nodemanager.aux-services.spark_shuffle.system-classes is absent, yarn will treat yarn.nodemanager.aux-services.spark_shuffle.class as the system classes, and use system ClassLoader rather than AuxServiceClassLoader to load aux service entry class, then cause ClassNotFound exception.

How was this patch tested?

Existing UTs.

For code changes:

• Does the title or this PR starts with the corresponding JIRA issue id (e.g. 'HADOOP-17799. Your PR title ...')?
• Object storage: have the integration tests been executed and the endpoint declared according to the connector-specific documentation?
• If adding new dependencies to the code, are these dependencies licensed in a way that is compatible for inclusion under ASF 2.0?
• If applicable, have you updated the LICENSE, LICENSE-binary, NOTICE-binary files?

[hadoop-yetus]

💔 -1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	0m 58s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 1s		No case conflicting files found.
+0 🆗	codespell	0m 1s		codespell was not available.
+1 💚	@author	0m 0s		The patch does not contain any @author tags.
-1 ❌	test4tests	0m 0s		The patch doesn't appear to include any new or modified tests. Please justify why no new tests are needed for this patch. Also please list what manual steps were performed to verify this patch.
			_ trunk Compile Tests _
+1 💚	mvninstall	37m 45s		trunk passed
+1 💚	compile	1m 51s		trunk passed with JDK Ubuntu-11.0.11+9-Ubuntu-0ubuntu2.20.04
+1 💚	compile	1m 36s		trunk passed with JDK Private Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10
+1 💚	checkstyle	0m 35s		trunk passed
+1 💚	mvnsite	0m 50s		trunk passed
+1 💚	javadoc	0m 45s		trunk passed with JDK Ubuntu-11.0.11+9-Ubuntu-0ubuntu2.20.04
+1 💚	javadoc	0m 38s		trunk passed with JDK Private Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10
+1 💚	spotbugs	1m 41s		trunk passed
+1 💚	shadedclient	25m 6s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	0m 45s		the patch passed
+1 💚	compile	1m 40s		the patch passed with JDK Ubuntu-11.0.11+9-Ubuntu-0ubuntu2.20.04
+1 💚	javac	1m 40s		the patch passed
+1 💚	compile	1m 29s		the patch passed with JDK Private Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10
+1 💚	javac	1m 29s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	0m 27s		the patch passed
+1 💚	mvnsite	0m 43s		the patch passed
+1 💚	javadoc	0m 36s		the patch passed with JDK Ubuntu-11.0.11+9-Ubuntu-0ubuntu2.20.04
+1 💚	javadoc	0m 31s		the patch passed with JDK Private Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10
+1 💚	spotbugs	1m 46s		the patch passed
+1 💚	shadedclient	24m 28s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	unit	23m 54s		hadoop-yarn-server-nodemanager in the patch passed.
+1 💚	asflicense	0m 33s		The patch does not generate ASF License warnings.
		128m 41s

Subsystem	Report/Notes
Docker	ClientAPI=1.41 ServerAPI=1.41 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-3816/1/artifact/out/Dockerfile
GITHUB PR	#3816
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell
uname	Linux 30e725a7515d 4.15.0-163-generic #171-Ubuntu SMP Fri Nov 5 11:55:11 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	trunk / 24f9102
Default Java	Private Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10
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Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-3816/1/testReport/
Max. process+thread count	563 (vs. ulimit of 5500)
modules	C: hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager U: hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-3816/1/console
versions	git=2.25.1 maven=3.6.3 spotbugs=4.2.2
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[pan3793]

@aajisaka would you please take a look?

[aajisaka]

+1. The fix makes sense.

[aajisaka]

Thank you @pan3793 for your contribution!