TRAVIS: turn off upload python test code coverage

[jamesbeyond]

Description

Turn off upload python test code coverage from TRAVIS.
We are planing to upload C/CPP code coverage to coverall.io later on.

Pull request type

[ ] Fix
[ ] Refactor
[ ] Target update
[ ] Functionality change
[ ] Docs update
[x] Test update
[ ] Breaking change

Reviewers

@cmonr

[0xc0170]

Ci started

[0xc0170]

@jamesbeyond thinking about the release target for this. I am inclined for 5.13.

One question - this python test coverage goes to tools repository (so can be removed here and wont lose this test coverage) ?

[jamesbeyond]

Hi @0xc0170,
The python code coverage is not for https://github.com/ARMmbed/mbed-os-tools , it is for the tools folder inside mbed-os. the Travis still run the test and generate coverage, but it is just not uploading them, but we are not loosing anything. if there is some mirror repos we can upload to there.

Turn this python code coverage off is for uploading the C/CPP code coverage. which is more useful. I don't think we need to wait for 5.13. because it is not a function change. will not have impact to anyone.
Surely it can be announced in 5.13, let people aware of that.