[jdk11u-dev] RFR: 8262862: Harden tests sun/security/x509/URICertStore/ExtensionsWithLDAP.java and krb5/canonicalize/Test.java

[Aleksey Shipilev]

Clean backport to match `11.0.13-oracle`.

Additional testing:
 - [x] Affected tests still pass

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

Commit messages:
 - Backport e1cad97049642ab201d53ff608937f7e7ef3ff3e

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/245/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=245&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262862
  Stats: 32 lines in 2 files changed: 7 ins; 20 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/245.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/245/head:pull/245

PR: https://git.openjdk.java.net/jdk11u-dev/pull/245