HDFS-17251. RBF: Optimize MountTableResolver#TRASH_PATTERN

[hfutatzhanghb]

Description of PR

We should make the length of date string of MountTableResolver#TRASH_PATTERN have fixed length.

because the trash dirs look like below pattern:

/user/hdfs/.Trash/231113002000

the data string has a fixed length of 12.

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	19m 20s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 0s		No case conflicting files found.
+0 🆗	codespell	0m 1s		codespell was not available.
+0 🆗	detsecrets	0m 1s		detect-secrets 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	48m 19s		trunk passed
+1 💚	compile	0m 40s		trunk passed with JDK Ubuntu-11.0.20.1+1-post-Ubuntu-0ubuntu120.04
+1 💚	compile	0m 37s		trunk passed with JDK Private Build-1.8.0_382-8u382-ga-1~20.04.1-b05
+1 💚	checkstyle	0m 28s		trunk passed
+1 💚	mvnsite	0m 42s		trunk passed
+1 💚	javadoc	0m 41s		trunk passed with JDK Ubuntu-11.0.20.1+1-post-Ubuntu-0ubuntu120.04
+1 💚	javadoc	0m 29s		trunk passed with JDK Private Build-1.8.0_382-8u382-ga-1~20.04.1-b05
+1 💚	spotbugs	1m 20s		trunk passed
+1 💚	shadedclient	38m 37s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	0m 32s		the patch passed
+1 💚	compile	0m 34s		the patch passed with JDK Ubuntu-11.0.20.1+1-post-Ubuntu-0ubuntu120.04
+1 💚	javac	0m 34s		the patch passed
+1 💚	compile	0m 29s		the patch passed with JDK Private Build-1.8.0_382-8u382-ga-1~20.04.1-b05
+1 💚	javac	0m 29s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	0m 18s		the patch passed
+1 💚	mvnsite	0m 33s		the patch passed
+1 💚	javadoc	0m 28s		the patch passed with JDK Ubuntu-11.0.20.1+1-post-Ubuntu-0ubuntu120.04
+1 💚	javadoc	0m 23s		the patch passed with JDK Private Build-1.8.0_382-8u382-ga-1~20.04.1-b05
+1 💚	spotbugs	1m 23s		the patch passed
+1 💚	shadedclient	41m 25s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
-1 ❌	unit	22m 17s	/patch-unit-hadoop-hdfs-project_hadoop-hdfs-rbf.txt	hadoop-hdfs-rbf in the patch passed.
+1 💚	asflicense	0m 36s		The patch does not generate ASF License warnings.
		185m 30s

Reason	Tests
Failed junit tests	hadoop.hdfs.server.federation.router.TestRouterTrash

Subsystem	Report/Notes
Docker	ClientAPI=1.43 ServerAPI=1.43 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-6268/1/artifact/out/Dockerfile
GITHUB PR	#6268
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell detsecrets
uname	Linux 75d7c2fe7f8d 4.15.0-213-generic #224-Ubuntu SMP Mon Jun 19 13:30:12 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	trunk / 02c5687
Default Java	Private Build-1.8.0_382-8u382-ga-1~20.04.1-b05
Multi-JDK versions	/usr/lib/jvm/java-11-openjdk-amd64:Ubuntu-11.0.20.1+1-post-Ubuntu-0ubuntu120.04 /usr/lib/jvm/java-8-openjdk-amd64:Private Build-1.8.0_382-8u382-ga-1~20.04.1-b05
Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-6268/1/testReport/
Max. process+thread count	2612 (vs. ulimit of 5500)
modules	C: hadoop-hdfs-project/hadoop-hdfs-rbf U: hadoop-hdfs-project/hadoop-hdfs-rbf
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-6268/1/console
versions	git=2.25.1 maven=3.6.3 spotbugs=4.2.2
Powered by	Apache Yetus 0.14.0 https://yetus.apache.org

This message was automatically generated.

[goiri]

Can we have a test for this?