You need a add a dummy grouping for that in the matrix
Choose TestNo as RowGroup field
Add Category field as column group
Add a parent group for column group with expression as
=LEFT(Fields!Category.Value,1)
for the Category add option Add Total after
At this stage matrix looks like this

Now delete the row containing top column group (ie red one above)
Now run the report and you'll get desired output
ie below

The sample rdl can be found here
Sample RDL
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Visakh
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