HADOOP-19887. Improve GHA website workflow

[pan3793]

Description of PR

• Upgrade actions to the latest version
• Manage Maven cache via actions/setup-java
• Switch mvn to mvnw, so it always picks the requested version of maven, instead of using mvn shipped in OS or installed by actions/setup-java.

How was this patch tested?

I manually run those commands locally to ensure they work as expected.

For code changes:

• Does the title or this PR starts with the corresponding JIRA issue id (HADOOP-19887)?
• 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?

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[pan3793]

@slfan1989 could you please take a quick look? we need this to recover the website deployed, currently it picks an obsolete version of mvn installed by actions/setup-java, which violates the org.apache.maven.enforcer.rules.version.RequireMavenVersion
https://github.com/apache/hadoop/actions/runs/25535467127/job/74950312789

[slfan1989]

@pan3793 Thanks for the contribution! LGTM.

[pan3793]

thanks, merged to trunk (lint check pass, no need to wait for building pipeline as it does not touch the code)

[hadoop-yetus]

💔 -1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	18m 54s		Docker mode activated.
-1 ❌	patch	0m 5s		#8482 does not apply to trunk. Rebase required? Wrong Branch? See https://cwiki.apache.org/confluence/display/HADOOP/How+To+Contribute for help.

Subsystem	Report/Notes
Docker	ClientAPI=1.54 ServerAPI=1.54 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-8482/1/artifact/out/Dockerfile
GITHUB PR	#8482
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-8482/1/console
versions	git=2.43.0
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[pan3793]

this unfortunately does not work, and it was not caught in my local test as it has cache in ~/.m2, I pushed a hotfix to restore it b3cc7d0