Remove ByteTree serialization format

It was originally designed for faster trasmission of syntax trees from
C++ to SwiftSyntax, but superceded by the CLibParseActions. There's no
deserializer for it anymore, so let's just remove it.

utils/gyb_sourcekit_support/UIDs.py

@@ -52,8 +52,6 @@ UID_KEYS = [
     KEY('SourceText', 'key.sourcetext'),
     KEY('EnableSyntaxMap', 'key.enablesyntaxmap'),
     KEY('SyntaxTreeTransferMode', 'key.syntaxtreetransfermode'),
-    KEY('SyntaxTreeSerializationFormat',
-        'key.syntax_tree_serialization_format'),
     KEY('EnableStructure', 'key.enablesubstructure'),
     KEY('Description', 'key.description'),
     KEY('TypeName', 'key.typename'),
@@ -453,8 +451,4 @@ UID_KINDS = [
     KIND('SyntaxTreeOff', 'source.syntaxtree.transfer.off'),
     KIND('SyntaxTreeIncremental', 'source.syntaxtree.transfer.incremental'),
     KIND('SyntaxTreeFull', 'source.syntaxtree.transfer.full'),
-    KIND('SyntaxTreeSerializationJSON',
-         'source.syntaxtree.serialization.format.json'),
-    KIND('SyntaxTreeSerializationByteTree',
-         'source.syntaxtree.serialization.format.bytetree'),
 ]