HADOOP-19650. [ABFS][Backport-3.4] Fixing NPE when close() called on uninitialized AzureBlobFileSystem

[anujmodi2021]

Description of PR

PR on trunk: #7880
JIRA: https://issues.apache.org/jira/browse/HADOOP-19650

[hadoop-yetus]

🎊 +1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	6m 54s		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 1 new or modified test files.
			_ branch-3.4 Compile Tests _
+1 💚	mvninstall	26m 26s		branch-3.4 passed
+1 💚	compile	0m 22s		branch-3.4 passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	compile	0m 20s		branch-3.4 passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	checkstyle	0m 18s		branch-3.4 passed
+1 💚	mvnsite	0m 24s		branch-3.4 passed
+1 💚	javadoc	0m 23s		branch-3.4 passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	javadoc	0m 20s		branch-3.4 passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	spotbugs	0m 41s		branch-3.4 passed
+1 💚	shadedclient	19m 39s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	0m 20s		the patch passed
+1 💚	compile	0m 21s		the patch passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	javac	0m 21s		the patch passed
+1 💚	compile	0m 15s		the patch passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	javac	0m 15s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	0m 12s		hadoop-tools/hadoop-azure: The patch generated 0 new + 1 unchanged - 1 fixed = 1 total (was 2)
+1 💚	mvnsite	0m 19s		the patch passed
+1 💚	javadoc	0m 18s		the patch passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	javadoc	0m 18s		the patch passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	spotbugs	0m 45s		the patch passed
+1 💚	shadedclient	19m 33s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	unit	2m 3s		hadoop-azure in the patch passed.
+1 💚	asflicense	0m 25s		The patch does not generate ASF License warnings.
		81m 35s

Subsystem	Report/Notes
Docker	ClientAPI=1.51 ServerAPI=1.51 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-7889/1/artifact/out/Dockerfile
GITHUB PR	#7889
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell detsecrets
uname	Linux 6822d049569c 5.15.0-143-generic #153-Ubuntu SMP Fri Jun 13 19:10:45 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	branch-3.4 / cc51165
Default Java	Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
Multi-JDK versions	/usr/lib/jvm/java-11-openjdk-amd64:Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04 /usr/lib/jvm/java-8-openjdk-amd64:Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-7889/1/testReport/
Max. process+thread count	559 (vs. ulimit of 5500)
modules	C: hadoop-tools/hadoop-azure U: hadoop-tools/hadoop-azure
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-7889/1/console
versions	git=2.25.1 maven=3.6.3 spotbugs=4.2.2
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[anujmodi2021]

@steveloughran @ahmarsuhail
Let me know if this is good to merge.
Thanks