Use metadata to rewrite date params for dry run

[relud]

this handles query parameters as seen here

bigquery-etl/sql/moz-fx-data-shared-prod/mozilla_vpn_derived/funnel_ga_to_subscriptions_v1/metadata.yaml

Lines 9 to 11 in cc288f5

	scheduling:
	dag_name: bqetl_mozilla_vpn_site_metrics
	date_partition_parameter: date

and here

bigquery-etl/sql/moz-fx-data-shared-prod/mozilla_vpn_derived/protected_v1/metadata.yaml

Lines 9 to 15 in cc288f5

	scheduling:
	dag_name: bqetl_mozilla_vpn
	# destination is the whole table, not a single partition,
	# so don't use date_partition_parameter
	date_partition_parameter: null
	parameters:
	- "date:DATE:{{ds}}"

so that bqetl query schema update works for both those tables