Issue #11720: Kill surviving mutation in RequireThisCheck

[Vyom-Yadav]

#11720
Hardcoded mutation tested at #11771

Reports with hardcoded mutation (clean):

• DefaultConfig: https://checkstyle-diff-reports.s3.us-east-2.amazonaws.com/d1202e8_2022093015/reports/diff/index.html

This mutation falls in the category:

• Safely (no regressions) remove code to be covered

Rationale:

Without the condition if (toVisit == null), curNode = curNode.getParent(); will be executed even when toVisit != null, if toVisit != null, we will break from the loop
while (curNode != null && toVisit == null) and on the very next line after while loop, curNode gets updated curNode = toVisit;, so the previous assignment of
curNode = curNode.getParent();does not make a difference.