Avoiding == 0. or != 0. comparison for pFlow charge
@mhodgkin reported in ATLJETMET-796 that the charge of the pFlow object is compared to != 0.0 instead of using FLT_MIN. This has been hopefully changed now in all instances and also the comparisons to 1e-9 where changed to FLT_MIN
A similar MR will be created for release 21.2. I chose a separate MR given that some files differed between 21.0 and 21.2.
Also tagging @wbalunas, @williams and @khoo for their information.
Edited by Chris Malena Delitzsch