[jdt-core-dev] Removed test exclusion mechanism

["Jerome Lanneluc" <jerome_lanneluc@xxxxxxxxxx>]

I just removed the test exclusion mechanism from our test suites. This
exclusion mechanism was confusing when running individual test suites as
the tests were not excluded in this case. They were excluded only when
running the component test suites (such as
org.eclipse.jdt.core.tests.compiler.parser.TestAll)

The recommended way to exclude a test is to now change it from 'test...' to
'_test...' and add a TODO to remind us why it was excluded.

I converted the existing tests to use this mechanism. Note some tests were
excluded but I have no idea why, so the TODO is not very descriptive.
Please look at the tests you're responsible for and assess whether they are
valid tests, why they fail, and if they should be definitely removed.

Jerome