Summary:

• Linux_android_emu external_textures_integration_test is 2.00% flaky #150838 is flaky by nature; it's an emulator test.
• It is still important to run as its the only end-to-end test for external textures.
• it's expensive to run some tests on devices.
• we really want this to be a smoke test

Suggestion:

Add flakiness_threshold as optional to ci.yaml and check it here:
https://github.com/flutter/cocoon/blob/b20de7e2b65d5dd61618f0f4303c5b19eb541266/app_dart/lib/src/request_handlers/file_flaky_issue_and_pr.dart#L101-L104

Then we can tune our pain-threshold for specific tests.