Add source IP address and hostname to authentication failure logs (JENKINS-76220)

[sgscheffler]

Description

Adds source IP address and hostname to authentication failure log messages to help administrators identify which Jenkins node/agent is attempting to authenticate with incorrect credentials.

Changes

• Add getSourceInfo() helper method to capture request source information
• Include remote address and hostname in credential exception warnings
• Helps administrators identify which node/agent is using wrong credentials
• Uses Jakarta servlet API (non-deprecated)
• Gracefully handles cases where request context is unavailable

Example Output

Before:

WARNING: Credential exception trying to authenticate against XXX.YYY domain

After:

WARNING: Credential exception trying to authenticate against XXX.YYY domain from 192.168.1.100 (hostname.domain.com)

Fixes JENKINS-76220

Testing done

• Compiled successfully with mvn clean compile
• All existing tests pass with mvn clean test
• Manual code review: The getSourceInfo() method safely handles null request contexts by returning an empty string
• The change only affects log output and does not modify authentication behavior
• Tested local build with mvn hpi:run to verify plugin loads correctly

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests that demonstrate the feature works or the issue is fixed