Integration tests fail when trying to run multiple tests (from a directory) - "Unable to start the app on the device."

First file gets executed successfully, but additional test files all fail with "Unable to start the app on the device."

Running other test files one by one individually works just fine.

At the moment I am working around this by using a script in terminal to run every file individually, but it would be nice if I could have the IDE integration working.

Here is the full log:
```
/opt/flutter/bin/flutter --no-color test --machine -d linux integration_test
Testing started at 11:33 ...
Building Linux application...
/home/janez/PycharmProjects/trackself/desktopapp/linux/flutter/ephemeral/.plugin_symlinks/tray_manager/linux/tray_manager_plugin.cc:118:17: warning: 'app_indicator_new' is deprecated [-Wdeprecated-declarations]
✓ Built build/linux/x64/debug/bundle/trackself

Building Linux application...
/home/janez/PycharmProjects/trackself/desktopapp/linux/flutter/ephemeral/.plugin_symlinks/tray_manager/linux/tray_manager_plugin.cc:118:17: warning: 'app_indicator_new' is deprecated [-Wdeprecated-declarations]
✓ Built build/linux/x64/debug/bundle/trackself
Error waiting for a debug connection: The log reader stopped unexpectedly, or never started.
package:flutter_tools/src/test/integration_test_device.dart 65:86 IntegrationTestTestDevice.start
===== asynchronous gap ===========================
package:flutter_tools/src/test/flutter_platform.dart 682:51 FlutterPlatform._startTest.
===== asynchronous gap ===========================
package:flutter_tools/src/base/async_guard.dart 109:26 asyncGuard.

Failed to load "/home/janez/PycharmProjects/trackself/desktopapp/integration_test/widget/autocomplete_test.dart": Unable to start the app on the device.

Building Linux application...
/home/janez/PycharmProjects/trackself/desktopapp/linux/flutter/ephemeral/.plugin_symlinks/tray_manager/linux/tray_manager_plugin.cc:118:17: warning: 'app_indicator_new' is deprecated [-Wdeprecated-declarations]
✓ Built build/linux/x64/debug/bundle/trackself
Error waiting for a debug connection: The log reader stopped unexpectedly, or never started.
package:flutter_tools/src/test/integration_test_device.dart 65:86 IntegrationTestTestDevice.start
===== asynchronous gap ===========================
package:flutter_tools/src/test/flutter_platform.dart 682:51 FlutterPlatform._startTest.
===== asynchronous gap ===========================
package:flutter_tools/src/base/async_guard.dart 109:26 asyncGuard.

Failed to load "/home/janez/PycharmProjects/trackself/desktopapp/integration_test/widget/task_editor_datetime_test.dart": Unable to start the app on the device.

Building Linux application...
/home/janez/PycharmProjects/trackself/desktopapp/linux/flutter/ephemeral/.plugin_symlinks/tray_manager/linux/tray_manager_plugin.cc:118:17: warning: 'app_indicator_new' is deprecated [-Wdeprecated-declarations]
✓ Built build/linux/x64/debug/bundle/trackself
Error waiting for a debug connection: The log reader stopped unexpectedly, or never started.
package:flutter_tools/src/test/integration_test_device.dart 65:86 IntegrationTestTestDevice.start
===== asynchronous gap ===========================
package:flutter_tools/src/test/flutter_platform.dart 682:51 FlutterPlatform._startTest.
===== asynchronous gap ===========================
package:flutter_tools/src/base/async_guard.dart 109:26 asyncGuard.

Failed to load "/home/janez/PycharmProjects/trackself/desktopapp/integration_test/widget/profile_auth_integration_test.dart": Unable to start the app on the device.

Building Linux application...
/home/janez/PycharmProjects/trackself/desktopapp/linux/flutter/ephemeral/.plugin_symlinks/tray_manager/linux/tray_manager_plugin.cc:118:17: warning: 'app_indicator_new' is deprecated [-Wdeprecated-declarations]
✓ Built build/linux/x64/debug/bundle/trackself
Error waiting for a debug connection: The log reader stopped unexpectedly, or never started.
package:flutter_tools/src/test/integration_test_device.dart 65:86 IntegrationTestTestDevice.start
===== asynchronous gap ===========================
package:flutter_tools/src/test/flutter_platform.dart 682:51 FlutterPlatform._startTest.
===== asynchronous gap ===========================
package:flutter_tools/src/base/async_guard.dart 109:26 asyncGuard.

Failed to load "/home/janez/PycharmProjects/trackself/desktopapp/integration_test/widget/account_status_check_license_test.dart": Unable to start the app on the device.