Null safety for removeExecutor

Sometimes observed at end of (passing) WorkflowTest.executorStepRestart in 1.596.1:
Exception in thread "Executor #0 for slave0 : executing PlaceholderExecutable:job/demo/1/:null" java.lang.NullPointerException
	at hudson.model.Computer.removeExecutor(Computer.java:869)
	at hudson.model.Executor.run(Executor.java:272)

Squashed commits:
[73308b5] [FIXED JENKINS-27549] job loading can be broken by a NPE in a build trigger

Reduce the thread overhead in NodeMonitorUpdater.

[FIXED JENKINS-28419] - JenkinsLocationConfiguration::adminAddress can be reset

Before, if N nodes connected quickly, this would spawn N threads all
sleeping for 5 seconds before realizing they don't need to do anything.

[JENKINS-9283] Timezone Support for Scheduling

[FIXED JENKINS-17290] -  Corrected sort order of tables

[FIXED JENKINS-28446] - proper calculation of queue length in UnlabeledLoadStatistics

[FIXED JENKINS-28274] Update to the latest versions of maven-jar-plugin and maven-war-plugin.

[FIXED JENKINS-28455] Build History badges don't wrap

Fix ptBR translation

Use ConsistentHash's mass-add method.

Calling hash.add() in a tight loop gets very expensive. With a
good-sized queue & slave pool, this cost tens of seconds, but now it
costs tens of milliseconds.

[FIXED JENKINS-28425] Fix build history styling badness

[JENKINS-28446] - Introduce new API method in Queue to optimize the performance of UnlabeledLoadStatistics

This implementation does not create new methods in API, hence it can be backported.