The test run comment size should be limited

In extreme scenarios, a test run comment may end up with a lot of data, and if this pattern is repeated enough times it might eventually affect Jira performances when loading and trying to access all the test runs.

e.g.: A customer has automation that imports 10mb of text into the comment column for each test run and creates 1000 test runs of the same Test Execution. When accessing the testruns of this test execution this will result in ~10GB of Heap being used.