Update git hash for flutter/devtools (#485)

Fixes failing Dart to Flutter [autoroller](flutter/flutter#185773).

[Failure log](https://logs.chromium.org/logs/flutter/buildbucket/cr-buildbucket/8683154551376454241/+/u/run_test.dart_for_customer_testing_shard_and_subshard_None/stdout)
```
| Analyzing devtools_app...
|
| warning - test/shared/eval_integration_test.dart:123:43 - A value of type 'Object?' can't be returned by the 'onError' handler because it must be assignable to 'FutureOr<FutureFailedException>', as required by 'Future.then'. - invalid_return_type_for_then
|
| 1 issue found.
```

Caused by a new analyzer warning: https://dart-review.googlesource.com/c/sdk/+/498240

eval_integration_test.dart was [updated 2 weeks ago](flutter/devtools@e439571#diff-d7c828cbc9f16c59e1193c5a9f816177e84619072686c4d41715f9882d0c188cL123) to fix the problematic line.

This updates the git hash used for flutter/devtools customer testing to incorporate this change.

Author: b-luk

registry/flutter_devtools.test

@@ -7,7 +7,7 @@ fetch=git -c core.longPaths=true clone https://github.com/flutter/devtools.git t
 # NOTE: this commit hash should also match the hash in flutter_devtools_analysis.test.
 # The analysis and testing for DevTools have been split into two different
 # registry to speed up performance.
-fetch=git -c core.longPaths=true -C tests checkout 0c1d983a4dafa7999c24f66c6c6857ee7633a4fd
+fetch=git -c core.longPaths=true -C tests checkout dc1d7ad27e8e0a94fad4d8e0ba3f5aaebd06f68d
 
 setup.linux=./tool/flutter_customer_tests/setup.sh >> output.txt
 

registry/flutter_devtools_analysis.test

@@ -7,7 +7,7 @@ fetch=git -c core.longPaths=true clone https://github.com/flutter/devtools.git t
 # NOTE: this commit hash should also match the hash in flutter_devtools.test.
 # The analysis and testing for DevTools have been split into two different
 # registry to speed up performance.
-fetch=git -c core.longPaths=true -C tests checkout 0c1d983a4dafa7999c24f66c6c6857ee7633a4fd
+fetch=git -c core.longPaths=true -C tests checkout dc1d7ad27e8e0a94fad4d8e0ba3f5aaebd06f68d
 
 # Mock generation required. Otherwise the test code will show analysis errors.
 setup.linux=./tool/flutter_customer_tests/setup.sh >> output.txt