Postgres tests are flaky

[SanjayVas]

The following test targets are marked as flaky:
//src/test/kotlin/org/wfanet/measurement/integration/postgres:PostgresInProcessLifeOfAReportIntegrationTest
//src/test/kotlin/org/wfanet/measurement/reporting/deploy/postgres:PostgresMeasurementsServiceTest
//src/test/kotlin/org/wfanet/measurement/reporting/deploy/postgres:PostgresReportingSetsServiceTest
//src/test/kotlin/org/wfanet/measurement/reporting/deploy/postgres:PostgresReportsServiceTest

[SanjayVas]

If these tests tend to pass individually but be flaky when running multiple tests, it may be that these tests need more than one core. This can be indicated on the Bazel target using the cpu tag. For example:

tags = ["cpu:2"]