Match capped value of non-refundable federal credits in state credits

[PavelMakarchuk]

Fixes #5918

[MaxGhenis]

Please instead do #5928. Note that:

• Maine CDCC worksheet points to 1040 schedule 3 line 2
• Kansas K-40 instructions say to enter the amount allowed on f2441 (implies line 11, the capped value)

In general let's create variables for line numbers that are cited multiple times to avoid redundant code.

This will make this PR's code changes unnecessary, except for the new tests.

Then request another team member's review, I'll give the final pass.