[lworld] RFR: 8345070: [lworld] Correct ProblemList.txt for SinceChecker

[Roger Riggs]

Correct entry for SinceChecker to remove "jdk/" prefix.

-------------

Commit messages:
 - 8345070: [lworld] Correct ProblemList.txt for SinceChecker

Changes: https://git.openjdk.org/valhalla/pull/1309/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1309&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8345070
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/valhalla/pull/1309.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1309/head:pull/1309

PR: https://git.openjdk.org/valhalla/pull/1309