Change the defaults:

-histogram_size=0
+histogram_size=254

-histogram_type=SINGLE_PREC_HB
+histogram_type=DOUBLE_PREC_HB

Adjust the testcases:
- Some have ignorable changes in EXPLAIN outputs and
  more counter increments due to EITS table reads.
- Testcases that meaningfully depend on the old defaults
  are changed to use the old values.