[JENKINS-66301] Prepare vSphere for core Guava upgrade

[basil]

See JENKINS-65988 and JENKINS-66301. Jenkins core is using Guava 11.0.1, which was released on January 9, 2012. Jenkins core would like to upgrade to Guava 30.1.1, which was released on March 19, 2021. Plugins must be prepared to be compatible with both Guava 11.0.1 and Guava 30.1.1 in advance of this core transition.

In particular, this plugin has been identified as using the com.google.common.base.Stopwatch API, which has changed between Guava 11.0.1 and latest. The following methods exist in Guava 11.0.1 but not latest:

• Stopwatch#elapsedMillis()
• Stopwatch#elapsedTime(TimeUnit desiredUnit)
• Stopwatch#toString(int significantDigits)

To facilitate the Jenkins core transition, this plugin must be prepared and released such that it works with both Guava 11.0.1 and latest. This PR migrates away from the Stopwatch API and uses System#nanoTime directly.

[basil]

@pjdarton Thanks! Could this please be released? This would help facilitate the Guava upgrade effort in Jenkins core.

[pjdarton]

Released just now.