Change trialConcurrency of multi_phase example in integration test (#816)

* fix remote bug

* add document

* add document

* update

* update

* update

* update

* fix remote issue

* fix forEach

* update doc according to comments

* update

* update

* update

* remove 'any more'

* change multi_phast trial concurrency

test/config_test/multi_phase/multi_phase.test.yml

 authorName: nni
 experimentName: default_test
 maxExecDuration: 5m
-maxTrialNum: 16
-trialConcurrency: 8
+maxTrialNum: 8
+trialConcurrency: 4
 searchSpacePath: ./search_space.json
 
 tuner: