DENG-3162 - limit 2 views to only go back to 10/1/23 (#5245)

* DENG-3162 - limit 2 views to only go back to 10/1/23

* DENG-3162 - add comments explaining the new filter

sql/moz-fx-data-marketing-prod/ga/www_site_downloads/view.sql

@@ -5,3 +5,5 @@ SELECT
   *
 FROM
   `moz-fx-data-marketing-prod.ga_derived.www_site_downloads_v2`
+WHERE
+  `date` >= '2023-10-01' --filter out data earlier since downloads not fully set up before this date

sql/moz-fx-data-marketing-prod/ga/www_site_metrics_summary/view.sql

@@ -5,3 +5,5 @@ SELECT
   *
 FROM
   `moz-fx-data-marketing-prod.ga_derived.www_site_metrics_summary_v2`
+WHERE
+  `date` >= '2023-10-01' --filter out data earlier since downloads not fully set up before this date