Lack of test isolation between CompletionTests and CompletionTests2

[stephan-herrmann]

The following tweaks in RunCompletionModelTests will cause failures:

• add CompletionTests2 to the suite before CompletionTests
• comment all other test classes
• run RunCompletionModelTests
• 2 failures:
  • CompletionTests2.testBug410207c() (that's an instance of #1190)
  • CompletionTests.test270436a() unexpected proposal

Now change CompletionTests.suite() from using BYTECODE_DECLARATION_ORDER to ALPHABETICAL_SORT:

• number of failures goes up to 20! I haven't even started to analyze this.

[stephan-herrmann]

Note, that above observations were on top of other pending fixes:

• #1077 where I already fixed the broken cleanup of CompletionTests2.testChangeInternalJar().
• proposed fix for #1203, without that results are:
  • ALPHABETICAL_SORT -> a complete freeze in CompletionTests.testBug351444()
  • BYTECODE_DECLARATION_ORDER -> 14 failures instead of 2

[jarthana]

I find most, (if not all, but need to be confirmed) failures are due to the tests setting the properties with JavaCore.setOptions but not applying them on the test project. Will confirm and produce a PR for M2.