Switch the TSV Zeek logs to be UTF8 by default.

There is a paired zeek-testing branch for some updates there.

testing/btest/scripts/base/frameworks/logging/ascii-escape-binary.zeek

@@ -2,6 +2,8 @@
 # @TEST-EXEC: btest-diff test.log
 # @TEST-EXEC: btest-diff output
 
+redef LogAscii::enable_utf_8 = F;
+
 module Test;
 
 export {