[TestOnly][Build] Support to collect the test coverage in cobertura format

[xumia]

What I did [Build] Support to collect the test coverage in cobertura format.

1. Collect the coverage inside of the docker container, only publish the coverage that does not have dependency on the coverage object file (gcno), reduce the file size a lot.
2. Export the build dir, make sure it works fine to collect the coverage info in an environment different from the build environment.
3. Simplify the coverage collection logic, disable the gcov stage.

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