Fix ArrayIndexOutOfBoundsException in ThrowableStackTraceRenderer if concurrently modifying the stacktrace of a throwable while rendering it

Closes #3940

Checklist

Before we can review and merge your changes, please go through the checklist below. If you're still working on some items, feel free to submit your pull request as a draft—our CI will help guide you through the remaining steps.

✅ Required checks

• License: I confirm that my changes are submitted under the Apache License, Version 2.0.

• Commit signatures: All commits are signed and verifiable. (See GitHub Docs on Commit Signature Verification).

• Code formatting: The code is formatted according to the project’s style guide.

  How to check and fix formatting

  • To check formatting: ./mvnw spotless:check
  • To fix formatting: ./mvnw spotless:apply

  See the build instructions for details.

• Build & Test: I verified that the project builds and all unit tests pass.

  How to build the project

  Run: ./mvnw verify

  See the build instructions for details.

🧪 Tests (select one)

• I have added or updated tests to cover my changes.
• No additional tests are needed for this change.

📝 Changelog (select one)

• I added a changelog entry in src/changelog/.2.x.x. (See Changelog Entry File Guide).
• This is a trivial change and does not require a changelog entry.