Add info messages for expected errors in test runs

[AgentHagu]

What is the purpose of this pull request?

• Documentation update
• Bug fix
• Feature addition or enhancement
• Code maintenance
• DevOps
• Improve developer experience
• Others, please explain:

Overview of changes:
Fixes #2612

This PR adds info messages for developers to inform them of the errors they should expect to see during npm run test. It also updates the developer guide to inform developers of these messages and errors:

Anything you'd like to highlight/discuss:
These changes are derived from the PR #2639

Testing instructions:

1. Run npm run build:backend
2. Run npm run test
3. Verify that there are accompanying info messages to inform developers about the expected logged errors

Proposed commit message: (wrap lines at 72 characters)
Add info messages for expected errors in test runs

Currently, there are some error messages that appear during
npm run test. These errors are expected to be logged due to
negative test cases involving includePanelProcessor.test.ts.

These error messages may be confusing to developers, as they may
be unaware that the errors are expected. To fix this, let's add info
messages to inform developers of any expected errors to be seen
during the test run.

---

Checklist: ☑️

• Updated the documentation for feature additions and enhancements
• Added tests for bug fixes or features
• Linked all related issues
• No unrelated changes

---

Reviewer checklist:

Indicate the SEMVER impact of the PR:

• Major (when you make incompatible API changes)
• Minor (when you add functionality in a backward compatible manner)
• Patch (when you make backward compatible bug fixes)

At the end of the review, please label the PR with the appropriate label: r.Major, r.Minor, r.Patch.

Breaking change release note preparation (if applicable):

• To be included in the release note for any feature that is made obsolete/breaking

Give a brief explanation note about:

• what was the old feature that was made obsolete
• any replacement feature (if any), and
• how the author should modify his website to migrate from the old feature to the replacement feature (if possible).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 52.84%. Comparing base (9dce090) to head (0ebe1d2).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2702      +/-   ##
==========================================
+ Coverage   52.80%   52.84%   +0.04%     
==========================================
  Files         130      130              
  Lines        7162     7162              
  Branches     1514     1591      +77     
==========================================
+ Hits         3782     3785       +3     
+ Misses       3225     3072     -153     
- Partials      155      305     +150     

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[tlylt]

Suggested change

	If you're adding tests that are expected to log errors to the console, make sure to **update the corresponding info messages** in the test logs.
	If you're adding tests that are expected to log new errors to the console, make sure to **update the corresponding info messages** in the test logs.