RFR: 8335150: Test LogGeneratedClassesTest.java fails on rpmbuild mock enviroment [v4]

[SendaoYan]

> Hi all,
> Test `test/jdk/java/lang/invoke/lambda/LogGeneratedClassesTest.java` fails on rpm build mock environment. The `df -h` command return fail `df: cannot read table of mounted file systems: No such file or directory` on the rpm build mock environment also. I think it's a environmental issue, and the environmental issue should not cause the test fails, it should skip the test.
> 
> The rpmbuild mock enviroment is like a sandbox, which created by `chroot` shell command, in the rpmbuild mock enviroment, `df -h` report `cannot read table of mounted file systems`, and java Files.getFileStore also throw `IOException`. We want to build and test the jdk in this `sandbox`, and the default jtreg work directory is `JTWork` in current directory, so this testcase will report fails.
> 
> Only change the testcase, the change has been verified locally, no risk.

SendaoYan has updated the pull request incrementally with one additional commit since the last revision:

  add the exception's toString() into SkipException

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/19905/files
  - new: https://git.openjdk.org/jdk/pull/19905/files/9c7946f8..b3af3f87

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19905&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19905&range=02-03

  Stats: 2 lines in 1 file changed: 0 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/19905.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19905/head:pull/19905

PR: https://git.openjdk.org/jdk/pull/19905