Use approximate client count in GLAM scalar_percentiles_v1 (#3039)

This is a follow-up to https://github.com/mozilla/bigquery-etl/pull/3037 which unblocked `scalar_bucket_counts_v1`.
`scalar_percentiles_v1` uses the same source table (`clients_scalar_aggregates_v1`) and started failing today with the same error (disk/memory limits exceeded for shuffle operations).

`APPROX_COUNT_DISTINCT` used here runs HLL under the hood. The reason for using it here is that we can't split the aggregation here into two stages as in the aforementioned PR due to quantiles calculation.

I have run this query locally and confirmed that it works.

bigquery_etl/glam/templates/scalar_percentiles_v1.sql

@@ -23,7 +23,7 @@ percentiles AS (
         {{ aggregate_attributes }},
         agg_type AS client_agg_type,
         'percentiles' AS agg_type,
-        COUNT(DISTINCT(client_id)) AS total_users,
+        APPROX_COUNT_DISTINCT(client_id) AS total_users,
         APPROX_QUANTILES(value, 1000) AS aggregates
     FROM
         all_combos

sql/glam-fenix-dev/glam_etl/org_mozilla_fenix_glam_nightly__scalar_percentiles_v1/query.sql

@@ -52,8 +52,8 @@ percentiles AS (
     key,
     agg_type AS client_agg_type,
     'percentiles' AS agg_type,
-    COUNT(DISTINCT(client_id)) AS total_users,
-    APPROX_QUANTILES(value, 100) AS aggregates
+    APPROX_COUNT_DISTINCT(client_id) AS total_users,
+    APPROX_QUANTILES(value, 1000) AS aggregates
   FROM
     all_combos
   GROUP BY
@@ -69,7 +69,10 @@ percentiles AS (
 )
 SELECT
   * REPLACE (
-    mozfun.glam.map_from_array_offsets([5.0, 25.0, 50.0, 75.0, 95.0], aggregates) AS aggregates
+    mozfun.glam.map_from_array_offsets_precise(
+      [0.1, 1.0, 5.0, 25.0, 50.0, 75.0, 95.0, 99.0, 99.9],
+      aggregates
+    ) AS aggregates
   )
 FROM
   percentiles

tests/sql/glam-fenix-dev/glam_etl/org_mozilla_fenix_glam_nightly__scalar_percentiles_v1/test_minimal/expect.yaml

@@ -1,5 +1,9 @@
 - agg_type: percentiles
   aggregates:
+  - key: '0.1'
+    value: 4.0
+  - key: '1'
+    value: 4.0
   - key: '5'
     value: 4.0
   - key: '25'
@@ -10,6 +14,10 @@
     value: 8.0
   - key: '95'
     value: 8.0
+  - key: '99'
+    value: 8.0
+  - key: '99.9'
+    value: 8.0
   app_build_id: '*'
   app_version: 84
   channel: '*'