The System image config details are not enclosed between " " (inverted commas) thus the AVD does not launch in a multi config job. 

Console log:

Check in BOLD, it should be enclosed in inverted commas.

[android] /Users/mobile_team/Library/Android/sdk/tools/bin/avdmanager create avd f c 512M -n hudson_en-US_720_1080x920_android-28_google_apis-x86_multiConfigTestJob-density-xxhdpi-os-21-resolution-1080x1920-29 -k system-images;android-28;google_apis;x86 --tag google_apis

Required:

[android] /Users/mobile_team/Library/Android/sdk/tools/bin/avdmanager create avd f c 512M -n hudson_en-US_720_1080x920_android-28_google_apis-x86_multiConfigTestJob-density-xxhdpi-os-21-resolution-1080x1920-29 -k "system-images;android-28;google_apis;x86" --tag google_apis

Enclosing this in inverted commas will enable us the run the multiConfig matrix job successfully with "keep emulator in job workspace" option enabled.

Full console logs in https://issues.jenkins-ci.org/browse/JENKINS-56282