Make syzygy recipes explicitly set GIT_MODE

scripts/slave/recipes/syzygy/coverage.expected/full_master_client_syzygy_Syzygy_Coverage.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]\\scripts\\slave\\kill_processes.py"
     ],
     "name": "taskkill"
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::bot_update]\\resources\\bot_update.py",
       "--master",
       "master.client.syzygy",
       "--builder",
       "Syzygy Coverage",
       "--slave",
       "vm331-m3",
       "--spec",
-      "cache_dir = '[GIT_CACHE]'\nsolutions = [{'deps_file': 'DEPS', 'managed': False, 'name': 'src', 'url': 'https://chromium.googlesource.com/external/github.com/google/syzygy.git/'}, {'deps_file': 'DEPS', 'managed': False, 'name': 'src-internal', 'url': 'https://chrome-internal.googlesource.com/chrome/syzygy/internal.DEPS.git'}]",
+      "cache_dir = '[GIT_CACHE]'\nsolutions = [{'deps_file': 'DEPS', 'managed': False, 'name': 'src', 'url': 'https://chromium.googlesource.com/external/github.com/google/syzygy.git/'}, {'deps_file': '.DEPS.git', 'managed': False, 'name': 'src-internal', 'url': 'https://chrome-internal.googlesource.com/chrome/syzygy/internal.DEPS.git'}]",
       "--root",
       "src",
       "--revision_mapping_file",
       "{\"src\": \"got_revision\"}",
       "--git-cache-dir",
       "[GIT_CACHE]",
       "--output_json",
       "/path/to/tmp/json",
       "--revision",
       "src@0e9f25b1098271be2b096fd1c095d6d907cf86f7",
@@ skipping 100 matching lines @@
     "~followup_annotations": [
       "@@@STEP_LINK@coverage_report@https://syzygy-archive.commondatastorage.googleapis.com/builds/coverage/f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9/index.html@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]