RFR: 8281170: Test jdk/tools/jpackage/windows/WinInstallerIconTest always fails on Windows 11

[Alexey Semenyuk]

Code clean up. Remove obsolete comments, unused imports, and unneeded jtreg test parameter.
Fix the code to handle the case when installers are not created and there is nothing to verify in the test.

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Commit messages:
 - 8281170: Test jdk/tools/jpackage/windows/WinInstallerIconTest always fails on Windows 11

Changes: https://git.openjdk.java.net/jdk/pull/7481/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7481&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8281170
  Stats: 46 lines in 1 file changed: 12 ins; 19 del; 15 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7481.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7481/head:pull/7481

PR: https://git.openjdk.java.net/jdk/pull/7481