fix: replace integrationTest task with build task when making gradle plugin release (#3828)
fix: replace integrationTest task with build task when making gradle plugin release (#3828)

Currently the release build for jib-gradle-plugin additionally runs integration tests before publishing to plugin portal.

The recent Kokoro release environment changes introduced a number of compatibility issues in our current integration test suite. After attempting patching workarounds, this PR replaces the integration test check with full build (including unit tests) instead.
GoogleContainerTools/jib,GoogleContainerTools/jib,GoogleContainerTools/jib,GoogleContainerTools/jib