HBASE-29028 Backport missing UI patches to branch-2

[PDavid]

Cherry-picked the following patches which were missing on branch-2 branch. Most of these applied as a clean cherry-pick (without conflicts). Unfortunately there were some which had conflicts and I manually resolved them.
Each commit message contains from which commit it was cherry-picked from.

• HBASE-24624 Optimize table.jsp code (HBASE-24624 Optimize table.jsp code #1963) - ⚠️ This did not apply cleanly - had to resolve conflicts manually
• HBASE-25402 Sorting order by start key or end key is not considering empty start key/end key (HBASE-25402 HBase UI: sorting order by start key or end key is not considering empty start key/end key #2955)
• HBASE-28778 NPE may occur when opening master-status or table.jsp or procedure.jsp while Master is initializing (HBASE-28778 NPE may occur when opening master-status or table.jsp or procedure.js… #6152)
• HBASE-20452 Master UI: Table merge button should validate required fields before submit

Is it OK to have multiple patches in one PR like this or would you prefer having a separate PR for each commit?

[Apache-HBase]

🎊 +1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	0m 45s		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.
			_ branch-2 Compile Tests _
+1 💚	mvninstall	2m 49s		branch-2 passed
+1 💚	spotless	0m 42s		branch has no errors when running spotless:check.
			_ Patch Compile Tests _
+1 💚	mvninstall	2m 38s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	spotless	0m 41s		patch has no errors when running spotless:check.
			_ Other Tests _
+1 💚	asflicense	0m 12s		The patch does not generate ASF License warnings.
		8m 52s

Subsystem	Report/Notes
Docker	ClientAPI=1.47 ServerAPI=1.47 base: https://ci-hbase.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-6548/1/artifact/yetus-general-check/output/Dockerfile
GITHUB PR	#6548
Optional Tests	dupname asflicense javac codespell detsecrets spotless
uname	Linux 5469aa18fc1a 5.4.0-200-generic #220-Ubuntu SMP Fri Sep 27 13:19:16 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/hbase-personality.sh
git revision	branch-2 / f69098e
Default Java	Eclipse Adoptium-11.0.23+9
Max. process+thread count	78 (vs. ulimit of 30000)
modules	C: hbase-server U: hbase-server
Console output	https://ci-hbase.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-6548/1/console
versions	git=2.34.1 maven=3.9.8
Powered by	Apache Yetus 0.15.0 https://yetus.apache.org

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[PDavid]

Closing this in favor of #6551 (new Jira ticket ID)