Fix spacing around end markers

[isaac091]

Also a small change to not count headers as elements that need to be placed.

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This change is 

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 88.93%. Comparing base (cd21706) to head (a3290b8).

Files with missing lines	Patch %	Lines
...corpora/place_markers_usfm_update_block_handler.py	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #198      +/-   ##
==========================================
- Coverage   88.94%   88.93%   -0.01%     
==========================================
  Files         282      282              
  Lines       17062    17066       +4     
==========================================
+ Hits        15175    15178       +3     
- Misses       1887     1888       +1     

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[ddaspit]

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @Enkidu93)