[CI] tests failing for the "run all image tests"

[MarcusDenker]

When re-loading in Pharo12 the packages and then run all tests (of Pharo), we have some strange failures:

testOnlyWeakSubscriptions

✗ #testOnlyWeakSubscriptions (4ms)
TestFailure: Got an Array(an AnnouncementSubscription (RPackageTest>>#testAddClass subscribes to ClassRecategorized)) instead of #(). 

MicPharoPackageCommentResourceReferenceTest

MicPharoPackageCommentResourceReferenceTest
 ✗ #testLoadDirectory_emptyPrefix (17ms)
#first was sent to nil

Lots of SystemDependency tests and testFilesShouldNotDependOnRandom

 ✗ #testFilesShouldNotDependOnRandom (3500ms)
KeyNotFound: key #ClassForTestToBeDeleted29 not found in SystemDictionary

[MarcusDenker]

fixed!