Modernize lts-candidate-stats script

[NotMyFault]

The change proposed rewrites the script in bash, given:

Caught: BUG! exception in phase 'semantic analysis' in source unit '/Users/alex/github/jenkins/a' Unsupported class file major version 69
BUG! exception in phase 'semantic analysis' in source unit '/Users/alex/github/jenkins/a' Unsupported class file major version 69
Caused by: java.lang.IllegalArgumentException: Unsupported class file major version 69

Took me some time to get a working version with the JIRA API, a 1:1 conversion produced nothing but gibberish.
For 2.528.1, this produces

Latest core version: jenkins-2.529

Fixed:
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- [JENKINS-76135] Jenkins does not compile with eclipse (https://issues.jenkins.io/browse/JENKINS-76135)
- [JENKINS-76114] Setup wizard plugin list does not show All/None/Suggested (regression in 2.527) (https://issues.jenkins.io/browse/JENKINS-76114)
- [JENKINS-76002] String comparison in JS when numbers are expected (https://issues.jenkins.io/browse/JENKINS-76002)

Postponed:
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- [JENKINS-16341] Memory leak in createJavaScriptProxy (https://issues.jenkins.io/browse/JENKINS-16341)
- [JENKINS-76075] Optimise LogRotator working in weak BuildReference mode (https://issues.jenkins.io/browse/JENKINS-76075)

Given we use autolinks in core, the JENKINS- reference is always clickable, the URL is just for console usage, if desired.
This matches the output of jenkinsci/jenkins#11130, just swapped, given I value fixes higher than postpones.

Fixes #384

[timja]

Works on my machine, @MarkEWaite possible for you to test too?

[MarkEWaite]

Thanks very, very much! @lemeurherve and I were wrestling with issues with the predecessor script on his macOS machine. I was wrestling with issues on my Red Hat Enterprise Linux machine and had to revert to my Ubuntu machine.

I've made several updates to the script based on my testing. I have not tested my revisions on a macOS machine. @timja or @lemeurherve , could you test it on macOS?

[MarkEWaite]

Thanks! I confirmed that the script runs for me on Linux. Thanks very, very much for the rewrite!

The script works well on my Ubuntu 22.04 computer with xmllint 20913 and on my Fedora 42 computer with xmllint 21210.

It does not show output on my Red Hat Enterprise Linux 8 computer with xmllint 20907.

[timja]

Works on my mac