Improve column support when there is a spacer

[jakejackson1]

Description

Better calculate when Gravity Forms would insert a spacer into the form, so we can correctly end a row in the PDF.

Testing instructions

1. Create a form with drag and drop columns
2. Set the width of a field in a column to only take up some of the space
3. Add additional rows and columns with a similar configuration
4. Add a PDF to the form
5. Preview the PDF

Checklist:

• [x] I've tested the code.
• [x] My code is easy to read, follow, and understand
• [ ] My code follows the accessibility standards.
• [x] My code has proper inline documentation / docblocks.

Additional Comments

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.

Project coverage is 75.68%. Comparing base (bb5a359) to head (af25986). Report is 5 commits behind head on hot-patch.

Files with missing lines	Patch %	Lines
src/Helper/Helper_Field_Container_Gf25.php	0.00%	4 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## hot-patch #1590 +/- ## ============================================= - Coverage 75.70% 75.68% -0.02% ============================================= Files 251 251 Lines 13606 13609 +3 Branches 370 370 ============================================= Hits 10300 10300 - Misses 3298 3301 +3 Partials 8 8 ```

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