[pgadmin-hackers][patch] delete icon width in security labels form

Hello Hackers,

We found a discrepancy with the width of inserted columns in some backform
tables. It is at least present in Create Table -> Security [tab] ->
clicking [+] for new rows under each of Privileges and Security Labels. In
this case, the cell containing the delete icon is spaced differently.

After briefly investigating, it looks like width_percent_xx classes on too
many columns is to blame. We've attached a patch that resolves the
immediate issue by removing width_percent_50 from the last column of two
schemas. It feels like columns are overconstrained since by themselves
width percentages sum to 100%, but there is behavior that inserts
additional columns beyond those specified in the schema. For instance, the
unshifts in Backform.UniqueColCollectionControl.showGridControl in
backform.pgadmin.js

Let us know what you think of this removal of last-column constraint as an
approach.

Thanks,
Joao and George