integration tests fixes & upgrades

[dataders]

• changes how CircleCI clones submodules, so that the commits to which they are pinned are actually checkout out properly
• moved submodules to the correct commit
• makes pausing/resuming Synapse db more fault tolerant
• adds shim for `dbt_date.from_unixtimestamp()
• tweaks the dbt_expectations.test_expect_column_stdev_to_be_between shims because of an error message