TEZ-4473: Remove pointless MDC_LOGGING message from logs if there is no custom MDC key.

[ayushtkn]

No description provided.

[tez-yetus]

💔 -1 overall

Vote	Subsystem	Runtime	Comment
+0 🆗	reexec	26m 0s	Docker mode activated.
		_ Prechecks _
+1 💚	dupname	0m 0s	No case conflicting files found.
+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.
		_ master Compile Tests _
+0 🆗	mvndep	6m 1s	Maven dependency ordering for branch
+1 💚	mvninstall	12m 27s	master passed
+1 💚	compile	1m 10s	master passed with JDK Ubuntu-11.0.19+7-post-Ubuntu-0ubuntu122.04.1
+1 💚	compile	1m 9s	master passed with JDK Private Build-1.8.0_362-8u372-gaus1-0ubuntu122.04-b09
+1 💚	checkstyle	1m 17s	master passed
+1 💚	javadoc	1m 20s	master passed with JDK Ubuntu-11.0.19+7-post-Ubuntu-0ubuntu122.04.1
+1 💚	javadoc	1m 10s	master passed with JDK Private Build-1.8.0_362-8u372-gaus1-0ubuntu122.04-b09
+0 🆗	spotbugs	0m 47s	Used deprecated FindBugs config; considering switching to SpotBugs.
+1 💚	findbugs	2m 19s	master passed
		_ Patch Compile Tests _
+0 🆗	mvndep	0m 10s	Maven dependency ordering for patch
+1 💚	mvninstall	0m 38s	the patch passed
+1 💚	compile	0m 39s	the patch passed with JDK Ubuntu-11.0.19+7-post-Ubuntu-0ubuntu122.04.1
+1 💚	javac	0m 39s	the patch passed
+1 💚	compile	0m 34s	the patch passed with JDK Private Build-1.8.0_362-8u372-gaus1-0ubuntu122.04-b09
+1 💚	javac	0m 34s	the patch passed
+1 💚	checkstyle	0m 22s	the patch passed
+1 💚	whitespace	0m 0s	The patch has no whitespace issues.
+1 💚	javadoc	0m 34s	the patch passed with JDK Ubuntu-11.0.19+7-post-Ubuntu-0ubuntu122.04.1
+1 💚	javadoc	0m 34s	the patch passed with JDK Private Build-1.8.0_362-8u372-gaus1-0ubuntu122.04-b09
+1 💚	findbugs	1m 36s	the patch passed
		_ Other Tests _
+1 💚	unit	2m 18s	tez-api in the patch passed.
+1 💚	unit	0m 27s	tez-common in the patch passed.
+1 💚	asflicense	0m 24s	The patch does not generate ASF License warnings.
		62m 40s

Subsystem	Report/Notes
Docker	ClientAPI=1.43 ServerAPI=1.43 base: https://ci-hadoop.apache.org/job/tez-multibranch/job/PR-294/2/artifact/out/Dockerfile
GITHUB PR	#294
JIRA Issue	TEZ-4473
Optional Tests	dupname asflicense javac javadoc unit spotbugs findbugs checkstyle compile
uname	Linux 7f857fc8594b 4.15.0-212-generic #223-Ubuntu SMP Tue May 23 13:09:22 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	personality/tez.sh
git revision	master / d20f334
Default Java	Private Build-1.8.0_362-8u372-gaus1-0ubuntu122.04-b09
Multi-JDK versions	/usr/lib/jvm/java-11-openjdk-amd64:Ubuntu-11.0.19+7-post-Ubuntu-0ubuntu122.04.1 /usr/lib/jvm/java-8-openjdk-amd64:Private Build-1.8.0_362-8u372-gaus1-0ubuntu122.04-b09
Test Results	https://ci-hadoop.apache.org/job/tez-multibranch/job/PR-294/2/testReport/
Max. process+thread count	592 (vs. ulimit of 5500)
modules	C: tez-api tez-common U: .
Console output	https://ci-hadoop.apache.org/job/tez-multibranch/job/PR-294/2/console
versions	git=2.34.1 maven=3.6.3 findbugs=3.0.1
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[ayushtkn]

The reason for the change lies here:
https://issues.apache.org/jira/browse/TEZ-4473?focusedCommentId=17735558&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-17735558

Th conf.getStrings(..,..) creates issues: The method description from the hadoop-code

https://github.com/apache/hadoop/blob/cebcb44d377710db6d4cff45f0b956f5a3372f51/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java#L2317-L2322

In case of null it returns the default value, which screws up the subsequent checks below

[abstractdog]

+1