Add time stamp for the job name and report name

[allieychen]

When running the integration tests, if there is already one running, an error will occur caused by the conflicting job names. Solution:

• Append the time stamp for the job name.
• Also append the time stamp for the report for easier validation.

Tested: Build and run triggers in Container Registry.

[coveralls]

Pull Request Test Coverage Report for Build 884

• 1 of 4 (25.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.02%) to 91.222%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
gcp_variant_transforms/testing/integration/run_preprocessor_tests.py	1	4	25.0%

Totals
Change from base Build 881:	-0.02%
Covered Lines:	4936
Relevant Lines:	5411

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💛 - Coveralls