Set batch priority on dedup and join

[stephen-soltesz]

This change adds QueryConfig.Priority for Dedup and Join jobs created by gardener using "Batch" priority. This change should avoid quota limits for interactive jobs recently seen in #410.

Fixes:

• Interactive jobRateLimitExceeded errors prevent daily jobs from completing #410

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This change is 

[coveralls]

Pull Request Test Coverage Report for Build 3588

• 10 of 10 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.1%) to 77.771%

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Totals
Change from base Build 3581:	0.1%
Covered Lines:	1242
Relevant Lines:	1597

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💛 - Coveralls

[cristinaleonr]

Reviewable status: complete! 1 of 1 approvals obtained (waiting on @stephen-soltesz)

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cloud/bq/ops.go line 120 at r2 (raw file):

			Q:      qs,
			DryRun: dryRun,
			// Perform Join as a batch job to avoid quota limits for interactive jobs.

I think you mean Dedup here.

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cloud/bq/ops_test.go line 119 at r2 (raw file):

			}
			if cfg.(*bigquery.QueryConfig).Priority != bigquery.BatchPriority {
				t.Errorf("TestValidateQueries() Dedup job priority is not Batch: %v", bigquery.BatchPriority)

And Join here.