To get the cost centers in a string on 1 row, you could do some config leveraging transforms and pivot steps.
This could get out of hand if you had a lot of cost centers, but setting this up to account for additional cost centers in the future would be as easy as extending out the formula. There could be a much easier process than this, but the first thing that comes to mind is this:
1) Create a new table from the import step of your cost center listing
2) Create 2 new columns in a formula step
a) Grouping and ="Group"
b) Cost Center Pivot and =Cost Center, set this as a numeric
3) Group the data by your new column "Grouping" & the original Cost Center column
4) Add another formula step and create a new column called New Column Count and =Row()+1
5) Add a Pivot Step
a) Pivot Row=Cost Center Pivot
b) Pivot Column=New Column Count
c) Pivot Value=Cost Center
At this point you should be left with a lot of columns, and 1 row of data with column headers 1,2,3,4 with a cost center code within each column.
6) Add another Formula step and create 1 additional column:
a) Cost Center Combination={1}&","&{2}&","&{3}&","&{4}&","&{5}....
You would build this formula out for however many cost centers you have + additional future cost centers. You would get an error as the formula wouldn't find the future columns, but it would prevent you from having to touch it in the future.
You would then be left with a Cost Center Combination that has all of your cost centers in string that will update depending on updates to your Cost Center Listing source file.
You would then need to add a column called Match set to "Match", go to your ITP transform, add the same column, then do a lookup into your transform with the pivot step, and bring back your string to put it on every row of your Cost Transparency Integration.
Things to watch out for:
1) Make sure you do the new table off of the import step to prevent a future circular reference.
2) Do not model this table or leverage it in the model as the Row()+1 can have a terrible impact on performance if it gets leveraged in an identifier.