Fix example polygerrit-ui command-line
Fix example polygerrit-ui command-line

java should be invoked from $(bazel info output) root. There is no
guarantee that $(which java) is compatible with the JDK that bazel
uses.

Change-Id: I339e4011fd2c84d2e8dd3d4e66730159ca625bbb

gerrit-review/gerrit,gerrit-review/gerrit,gerrit-review/gerrit,qtproject/qtqa-gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,qtproject/qtqa-gerrit,gerrit-review/gerrit,gerrit-review/gerrit,WANdisco/gerrit,gerrit-review/gerrit,GerritCodeReview/gerrit,WANdisco/gerrit,WANdisco/gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,WANdisco/gerrit,gerrit-review/gerrit,WANdisco/gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,WANdisco/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,WANdisco/gerrit