RFR: 8246099: Intermittent test failures in SandboxAppTest

[Kevin Rushforth]

This is a fix for an intermittent test failure, due to a timeout, in `SandboxAppTest` that we are starting to see on
some of our test machines.

The failure is happening because of a 10 second timeout in the launched application. This doesn't seem to be enough to
run the test to completion in all cases. I note that the similar launched apps, such as those launched by
`MainLauncherTest`, `ModuleLauncherTest`, and `JarLauncherTest` don't have a timeout (they just rely on the timeout
value of the launching test itself).

The app timeout was just added to prevent the test suite from hanging if the application were to get stuck, so there is
no need for it to be such a small value (nor to have it be less than the test timeout).

The proposed solution is to increase the app timeout to 30 seconds (up from 10) and the test timeout to 25 (up from 15).

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

Commit messages:
 - 8246099: Intermittent test failures in SandboxAppTest

Changes: https://git.openjdk.java.net/jfx/pull/241/files
 Webrev: https://webrevs.openjdk.java.net/jfx/241/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8246099
  Stats: 7 lines in 2 files changed: 0 ins; 0 del; 7 mod
  Patch: https://git.openjdk.java.net/jfx/pull/241.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/241/head:pull/241

PR: https://git.openjdk.java.net/jfx/pull/241