autotest: Run servod in recovery mode for AdminRepair

BUG=b:173151794
TEST=run local

GOOD DUT
test_that --args="servo_host=chromeos6-row18-rack3-labstation4 servo_port=9997 servo_serial=G1911051929" --board=eve --autotest_dir=.  chromeos6-row18-rack3-host3 servo_USBInstall
./server/autoserv -s --host-info-subdir host_info_store -m    chromeos6-row18-rack3-host3 --lab True --local-only-host-info True -R -r /tr/

BAD DUT
test_that --args="servo_host=chromeos6-row9-rack20-labstation servo_port=9998 servo_serial=C1706311408" --board=eve --autotest_dir=. chromeos6-row9-rack20-host3 servo_USBInstall
./server/autoserv -s --host-info-subdir host_info_store -m chromeos6-row9-rack20-host3 --lab True --local-only-host-info True -R -r /tr/

Change-Id: I2db6630acb3b77a4fe4a1583ef7dadd810a3a93c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2602603
Tested-by: Otabek Kasimov <otabek@google.com>
Reviewed-by: Garry Wang <xianuowang@chromium.org>
Commit-Queue: Otabek Kasimov <otabek@google.com>
diff --git a/server/hosts/servo_constants.py b/server/hosts/servo_constants.py
index bb74c05..2e83a8d 100644
--- a/server/hosts/servo_constants.py
+++ b/server/hosts/servo_constants.py
@@ -17,6 +17,7 @@
 # Indicates what type of servo setup, example value: REGULAR or DUAL_V4.
 SERVO_SETUP_ATTR = 'servo_setup'
 SERVO_SETUP_VALUE_DUAL_V4 = 'DUAL_V4'
+SERVO_RECOVERY_MODE = 'servo_recovery'
 SERVO_ATTR_KEYS = (
         SERVO_BOARD_ATTR,
         SERVO_HOST_ATTR,