[SourceKit] Remove duplicated kind definition. (#11968)

Compared to `CodeCompletionKeyword`, `CodeCompletionCodeCompleteKeyword` have the same string value and not used anywhere.
By inspecting PR #10604 where it is introduced, I think that is just a typo and can be removed safely.
diff --git a/tools/SourceKit/include/SourceKit/Core/ProtocolUIDs.def b/tools/SourceKit/include/SourceKit/Core/ProtocolUIDs.def
index a768f27..8f019c7 100644
--- a/tools/SourceKit/include/SourceKit/Core/ProtocolUIDs.def
+++ b/tools/SourceKit/include/SourceKit/Core/ProtocolUIDs.def
@@ -310,10 +310,9 @@
 KIND(DiagWarning, "source.diagnostic.severity.warning")
 KIND(DiagError, "source.diagnostic.severity.error")
 
-KIND(CodeCompletionKeyword, "source.codecompletion.keyword")
 KIND(CodeCompletionEverything, "source.codecompletion.everything")
 KIND(CodeCompletionModule, "source.codecompletion.module")
-KIND(CodeCompletionCodeCompleteKeyword, "source.codecompletion.keyword")
+KIND(CodeCompletionKeyword, "source.codecompletion.keyword")
 KIND(CodeCompletionLiteral, "source.codecompletion.literal")
 KIND(CodeCompletionCustom, "source.codecompletion.custom")
 KIND(CodeCompletionIdentifier, "source.codecompletion.identifier")