Support table prefix for sql reporter

In some environments zuul operators may have to rely on external
database providers. In this case it can be cumbersome to get extra
databases for each test environment. Adding an optional prefix to the
table names makes it possible to gracefully run several zuul
deployments against the same database and ensure they're still
isolated against each other.

Change-Id: Ib9948d6d74f4dc2453738f5d441e233e39e7f944
diff --git a/tests/fixtures/zuul-sql-driver-prefix.conf b/tests/fixtures/zuul-sql-driver-prefix.conf
new file mode 100644
index 0000000..1406474
--- /dev/null
+++ b/tests/fixtures/zuul-sql-driver-prefix.conf
@@ -0,0 +1,28 @@
+[gearman]
+server=127.0.0.1
+
+[scheduler]
+tenant_config=main.yaml
+
+[merger]
+git_dir=/tmp/zuul-test/merger-git
+git_user_email=zuul@example.com
+git_user_name=zuul
+
+[executor]
+git_dir=/tmp/zuul-test/executor-git
+
+[connection gerrit]
+driver=gerrit
+server=review.example.com
+user=jenkins
+sshkey=fake_id_rsa1
+
+[connection resultsdb]
+driver=sql
+dburi=$MYSQL_FIXTURE_DBURI$
+table_prefix=prefix_
+
+[connection resultsdb_failures]
+driver=sql
+dburi=$MYSQL_FIXTURE_DBURI$