Issue Jenkins-36718 - Fix DM_DEFAULT_ENCODING scanned by spotbugs

[programbeginnerTW]

See JENKINS-36718.

Testing done

• Clean compiled
• Manually tested Jenkins core as well as spotbugs to ensure no DM_DEFAULT_ENCODING remains.
• Specify using UTF-8 encoding to prevent relative problems.
• Run all SpotBugs check to proof the warnings were tackled.

Proposed changelog entries

• Fixed encoding issues in consoleNote.java, WindowsServiceLifecycle.java, and Textfile.java by specifying UTF-8 encoding instead of system default.

Proposed upgrade guidelines

N/A

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1. The Jira issue, if it exists, is well-described.
2. The changelog entries and upgrade guidelines are appropriate for the audience affected by the change (users or developers, depending on the change) and are in the imperative mood (see examples). Fill in the Proposed upgrade guidelines section only if there are breaking changes or changes that may require extra steps from users during upgrade.

Before the changes are marked as ready-for-merge:

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3. Changelog entries in the pull request title and/or Proposed changelog entries are accurate, human-readable, and in the imperative mood.
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[programbeginnerTW]

@oleg-nenashev , I saw this issue on Jira and mentioned you in the article. JENKINS-36718
Could you review this, please 🥹

[oleg-nenashev]

@programbeginnerTW thank for the pull request. I'm yet to return to the Jenkins core maintenance after a long sabbatical. I will try to take a look when I have a bit of a time, but there are also many other core maintainers around so you shouldn't depend on my response

Generally, I need to refresh my memory what will the agreements on default encoding. Using anything except system default is a potential breaking change. Maybe this it is safer to just use default

[oleg-nenashev]

@programbeginnerTW thank for the pull request. I'm yet to return to the Jenkins core maintenance after a long sabbatical. I will try to take a look when I have a bit of a time, but there are also many other core maintainers around so you shouldn't depend on my response

Generally, I need to refresh my memory what will the agreements on default encoding. Using anything except system default is a potential breaking change. Maybe this it is safer to just use default