opt: fix flake in TestExecBuild due to new stats cache refresh mechanism

This commit fixes a flake caused by the new stats cache update mechanism,
which refreshes the stats asynchronously. The solution is to retry the
test query until the new stats are available in the cache.

Fixes cockroachdb#50863

Release note: None

pkg/sql/opt/exec/execbuilder/testdata/stats

@@ -11,11 +11,26 @@ statement ok
 CREATE STATISTICS u ON u FROM uv;
 CREATE STATISTICS v ON v FROM uv
 
+query TTIIIB colnames
+SELECT
+  statistics_name,
+  column_names,
+  row_count,
+  distinct_count,
+  null_count,
+  histogram_id IS NOT NULL AS has_histogram
+FROM
+  [SHOW STATISTICS FOR TABLE uv]
+----
+statistics_name  column_names  row_count  distinct_count  null_count  has_histogram
+u                {u}           8          2               0           true
+v                {v}           8          7               0           true
+
 statement ok
 set enable_zigzag_join = false
 
 # Verify we scan index v which has the more selective constraint.
-query TTTTT
+query TTTTT retry
 EXPLAIN (VERBOSE) SELECT * FROM uv WHERE u = 1 AND v = 1
 ----
 ·     distributed  true         ·       ·