autotest: start servod with CONFIG=cr50.xml for DUTs in faft-cr50* pools

BUG=b:168215293
TEST=run repair on DUTs from/outside faft-cr50 pool

Change-Id: I0d9622f34b619162717e613f76bd5ea6442885bb
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2414949
Tested-by: Garry Wang <xianuowang@chromium.org>
Reviewed-by: Mary Ruthven <mruthven@chromium.org>
Reviewed-by: Otabek Kasimov <otabek@google.com>
Commit-Queue: Garry Wang <xianuowang@chromium.org>
diff --git a/server/hosts/servo_constants.py b/server/hosts/servo_constants.py
index 2adaf5f..1a02c23 100644
--- a/server/hosts/servo_constants.py
+++ b/server/hosts/servo_constants.py
@@ -31,6 +31,9 @@
                          'faft-pd-debug',
                          'faft_pd_debug'}
 
+# Prefix of pools that require servod cr50 config.
+CR50_CONFIG_POOL_PREFIX = 'faft-cr50'
+
 ENABLE_SSH_TUNNEL_FOR_SERVO = _CONFIG.get_config_value(
         'CROS', 'enable_ssh_tunnel_for_servo', type=bool, default=False)