[5pt] Total huc processing duration for branch 0 is incorrect

[RobHanna-NOAA]

There is a bug in calculating the branch 0 timing.
The intent:

• HUC duration: Total processing for the unit, branch 0 and all of it's branches included: Very top to very bottom of run_unit_wb.sh. This too is correct.

• Branch 0 processing by itself: In run_unit_wb.sh from the time it starts processing branch 0, appx line 130, to appx line 298, after usgs crosswalk. This one is incorrect.

• Remaining branches combined: in run_unit_wb.sh, appx line 314, to line 329. This one appears to be correct in logic.

It was detected in hand_4_6_0_0. It likely has been there since the beginning but was missed on testing.

Also.. see a likely related card : 1458: Missing processing time.