HDFS-16686. GetJournalEditServlet fails to authorize valid Kerberos request (#4724)

[snmvaughan]

Backport from trunk. GetJournalEditServlet uses request.getRemoteuser() to determine the remoteShortName for Kerberos authorization, which fails to match when the JournalNode uses its own Kerberos principal (e.g. jn/@).

This can be fixed by using the UserGroupInformation provided by the base DfsServlet class using the getUGI(request, conf) call.

• 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	10m 39s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 0s		No case conflicting files found.
+0 🆗	codespell	0m 0s		codespell was not available.
+0 🆗	detsecrets	0m 0s		detect-secrets was not available.
+1 💚	@author	0m 0s		The patch does not contain any @author tags.
+1 💚	test4tests	0m 0s		The patch appears to include 3 new or modified test files.
			_ branch-3.3 Compile Tests _
+1 💚	mvninstall	39m 18s		branch-3.3 passed
+1 💚	compile	1m 27s		branch-3.3 passed
+1 💚	checkstyle	1m 4s		branch-3.3 passed
+1 💚	mvnsite	1m 35s		branch-3.3 passed
+1 💚	javadoc	1m 45s		branch-3.3 passed
+1 💚	spotbugs	3m 36s		branch-3.3 passed
+1 💚	shadedclient	28m 51s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	1m 22s		the patch passed
+1 💚	compile	1m 16s		the patch passed
+1 💚	javac	1m 16s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
-0 ⚠️	checkstyle	0m 47s	/results-checkstyle-hadoop-hdfs-project_hadoop-hdfs.txt	hadoop-hdfs-project/hadoop-hdfs: The patch generated 4 new + 17 unchanged - 16 fixed = 21 total (was 33)
+1 💚	mvnsite	1m 25s		the patch passed
+1 💚	javadoc	1m 28s		the patch passed
+1 💚	spotbugs	3m 28s		the patch passed
+1 💚	shadedclient	27m 50s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
-1 ❌	unit	218m 56s	/patch-unit-hadoop-hdfs-project_hadoop-hdfs.txt	hadoop-hdfs in the patch passed.
+1 💚	asflicense	0m 59s		The patch does not generate ASF License warnings.
		343m 13s

Reason	Tests
Failed junit tests	hadoop.hdfs.TestReconstructStripedFileWithValidator
	hadoop.hdfs.TestRollingUpgrade
	hadoop.hdfs.server.blockmanagement.TestBlockTokenWithDFSStriped
	hadoop.hdfs.server.datanode.TestNNHandlesCombinedBlockReport
	hadoop.hdfs.server.balancer.TestBalancer

Subsystem	Report/Notes
Docker	ClientAPI=1.41 ServerAPI=1.41 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-4794/1/artifact/out/Dockerfile
GITHUB PR	#4794
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell detsecrets
uname	Linux b18814100895 4.15.0-191-generic #202-Ubuntu SMP Thu Aug 4 01:49:29 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	branch-3.3 / b9732a2
Default Java	Private Build-1.8.0_342-8u342-b07-0ubuntu1~18.04-b07
Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-4794/1/testReport/
Max. process+thread count	2246 (vs. ulimit of 5500)
modules	C: hadoop-hdfs-project/hadoop-hdfs U: hadoop-hdfs-project/hadoop-hdfs
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-4794/1/console
versions	git=2.17.1 maven=3.6.0 spotbugs=4.2.2
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[sunchao]

LGTM. Test failures look unrelated.