Make sure there are space between day and hour in the pattern
when we alternate date pattern for the change of hour cycle.

Bug: chromium:1170305
Change-Id: I2714111dcdedeefafdb854d1684f301786273303
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2654002
Commit-Queue: Frank Tang <ftang@chromium.org>
Reviewed-by: Frank Tang <ftang@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72418}