RFR: 8308608: [testbug] Use Util::waitForIdle instead of Toolkit::firePulse in system tests [v2]

[Karthik P K]

> Made changes to use Util::waitForIdle instead of Toolkit::firePulse in system tests. The test will wait for default value of 10 pulses to complete in the scene before executing the subsequent statements.

Karthik P K has updated the pull request incrementally with one additional commit since the last revision:

  Review comments

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Changes:
  - all: https://git.openjdk.org/jfx/pull/1230/files
  - new: https://git.openjdk.org/jfx/pull/1230/files/5f8045c0..73d9fcb9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1230&range=01
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1230&range=00-01

  Stats: 12 lines in 2 files changed: 0 ins; 8 del; 4 mod
  Patch: https://git.openjdk.org/jfx/pull/1230.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1230/head:pull/1230

PR: https://git.openjdk.org/jfx/pull/1230