Replace static icon references with symbol API

[NotMyFault]

This PR replaces a few static icon references with already used symbols through the symbol API. I plan to create a follow-up PR to address the leftover ones by adding the corresponding symbols.

noJob.groovy - the arrow shape change is marginal

Before

After

headerContent.jelly - Same symbol like on the profile page header

Before

After

<l:helpIcon>

Before

After

https://github.com/jenkinsci/jenkins/blob/master/war/src/main/resources/images/symbols/help-circle.svg

Proposed changelog entries

• Minor changes to empty state arrow icon and header user profile icon

Proposed upgrade guidelines

N/A

Submitter checklist

• (If applicable) Jira issue is well described
• Changelog entries and upgrade guidelines are appropriate for the audience affected by the change (users or developer, depending on the change) and are in the imperative mood. Examples
  • Fill-in the Proposed changelog entries section only if there are breaking changes or other changes which may require extra steps from users during the upgrade
• Appropriate autotests or explanation to why this change has no tests
• New public classes, fields, and methods are annotated with @Restricted or have @since TODO Javadoc, as appropriate.
• New deprecations are annotated with @Deprecated(since = "TODO") or @Deprecated(forRemoval = true, since = "TODO") if applicable.
• New or substantially changed JavaScript is not defined inline and does not call eval to ease future introduction of Content-Security-Policy directives (see documentation on jenkins.io).
• For dependency updates: links to external changelogs and, if possible, full diffs

Desired reviewers

@mention

Maintainer checklist

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

• There are at least 2 approvals for the pull request and no outstanding requests for change
• Conversations in the pull request are over OR it is explicit that a reviewer does not block the change
• Changelog entries in the PR title and/or Proposed changelog entries are accurate, human-readable, and in the imperative mood
• Proper changelog labels are set so that the changelog can be generated automatically
• If the change needs additional upgrade steps from users, upgrade-guide-needed label is set and there is a Proposed upgrade guidelines section in the PR title. (example)
• If it would make sense to backport the change to LTS, a Jira issue must exist, be a Bug or Improvement, and be labeled as lts-candidate to be considered (see query).

[basil]

@NotMyFault requested a review from basil 8 minutes ago

I have no idea how to review this change. If you want me to approve it, you just need to convince me that you've tested the change sufficiently. Your PR has no "Testing Done" section, so while I generally trust your work I have no way of verifying that.

[NotMyFault]

I have no idea how to review this change.

No worries, I updated the PR description to include a bit more context, but I wouldn't mind if you pass on your review to other UX SIG members, if you prefer that.

[timja]

Before / After screenshots of every component changed here would make this easier rather than just the result

[NotMyFault]

Before / After screenshots of every component changed here would make this easier rather than just the result

There we go 👍🏻

[timja]

Tested locally, looks good and thanks for the screenshots

[timja]

@NotMyFault I think this is worth adding to the changelog as a minor item, i.e. the user profile icon is changing

[NotMyFault]

This PR is now ready for merge. We will merge it after ~24 hours if there is no negative feedback.
Please see the merge process documentation for more information about the merge process.
Thanks!

[daniel-beck]

skip-changelog?

[timja]

Discussed in PR, could go either way

[daniel-beck]

Caused SECURITY-2886.