Code coverage reports should be correctly integrated with CI system

Currently our test coverage report upload mechanism is completely oblivious to the CI system logic.

For example, our CI system might do a test run of qt/qt-integration.git branch master-integration, then upload a coverage report to (Nokia LAN only)

https://qtmetrics.europe.nokia.com/testcoverage/bullseye/qt/qt-integration.git/master-integration

If the test results are good, the CI system will integrate to qt/qt.git branch master.
It will also copy the `master-integration' test results to `master' test results.

So, this can be thought of as "promoting" a candidate Qt to stable Qt, and at the same time promoting the test results. Similarly, we should promote the test coverage report.

In other words, this link should work for the latest qt/qt.git master, which it currently doesn't:

https://qtmetrics.europe.nokia.com/testcoverage/bullseye/qt/qt.git/master