disable buffer check on "testing" environment

[samsonasik]

Description
To clean up the buffer notice in "testing" environment which previously shows:

There were 3 risky tests:

1) CodeIgniter\CodeIgniterTest::testRunClosureRoute
Test code or tested code did not (only) close its own output buffers

2) CodeIgniter\CodeIgniterTest::testRun404OverrideByClosure
Test code or tested code did not (only) close its own output buffers

3) FeatureTestCaseTest::testEchoes
Test code or tested code did not (only) close its own output buffers

Checklist:

• Securely signed commits

[samsonasik]

From 3 down to 1:

There was 1 risky test:

1) FeatureTestCaseTest::testEchoes
Test code or tested code did not (only) close its own output buffers

[MGatner]

Wow thanks for this, such an annoyance. I looked into it at one point but was baffled where the issue was. Unfortunate that it is in app/ but this should affect TravisCI more than most users.

[MGatner]

We’re still getting one of these. @samsonasik any chance you could look at this last one since you seem to have dug into this issue?

1) FeatureTestCaseTest::testEchoes
366 Test code or tested code did not (only) close its own output buffers

[samsonasik]

I will check the last one when I have a chance ;)