Fix TestCodeCompletion::testCompletionPriority failures

A recent change in codeCompletionPriorityToMatchQuality() made the
priorities more fine-grained, which broke these tests.

The new expected matchQuality for XFAIL tests (2) is a hypothesis:
CCP_LocalDeclaration = 34
CCF_ExactTypeMatch = 4
CCF_SimilarTypeMatch = 2
For priority 34/4=8 matchQuality used to be 9, now 6 (verified).
For priority 34/2=17 matchQuality used to be 8, now 2 (hypothesized).