fix: [gax-java] Add speedy Bazel builds to Travis

[miraleung]

No description provided.

[codecov]

Codecov Report

Merging #1181 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #1181   +/-   ##
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  Coverage     78.98%   78.98%           
  Complexity     1194     1194           
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  Files           205      205           
  Lines          5259     5259           
  Branches        435      435           
=========================================
  Hits           4154     4154           
  Misses          933      933           
  Partials        172      172           

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[vam-google]

Thanks for doing it! Can we do it as a separate task? Now gradle and bazel go together as a part of the same build, while it would be cleaner if they were two different jobs (this is how ti is done for gapic-generator, for example).

Apart from that, it is simply awesome! Adding bazel build in CI was a long lasting "pending" task that nobody has actually ever done. As you noticed (given the other PR with a fix), the absence of it could cause bazel build for gax to fail even when gradlew one was fine.

[miraleung]

No problem. Done, split them into separate tasks.

[vam-google]

LGTM. Just an optional minor comment, feel free to ignore.