[448584] NPE on DBAnnotationsTest.testLengthAnnotationNegative()
execution

Remove TransactionCommitContext.removePackageAdapters() as it is useless
since CDOPackageUnit is not an Adapter anymore (see
https://bugs.eclipse.org/bugs/show_bug.cgi?id=406068 )

Task-Url: https://bugs.eclipse.org/bugs/show_bug.cgi?id=448584
Change-Id: I5db59d658165e0267a158fa41595e3d05d157a40
Signed-off-by: Esteban Dugueperoux <esteban.dugueperoux@obeo.fr>
[447912] CDOBranch.getBranches() doesn't return all sub branches

CDOBranch.getBranches() doesn't return all sub branches on first call if
another client has created a new branch on same parent
Addition of Bugzilla_447912_Test to test the scenario.
The fix consists in loading sub branches infos on
CDOBranchImpl.addChild() when branches == null.

Task-Url: https://bugs.eclipse.org/bugs/show_bug.cgi?id=447912
Change-Id: Ibcdda44548a6be49b0e6b94239b065ca33d4f3b8
Signed-off-by: Esteban Dugueperoux <esteban.dugueperoux@obeo.fr>