DEPR: Deprecate skip_footer in read_excel

[gfyoung]

For consistency with read_csv, which uses skipfooter.

[codecov]

Codecov Report

Merging #18836 into master will decrease coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master   #18836      +/-   ##
==========================================
- Coverage   91.64%   91.62%   -0.02%     
==========================================
  Files         154      154              
  Lines       51408    51406       -2     
==========================================
- Hits        47113    47101      -12     
- Misses       4295     4305      +10

Flag	Coverage Δ
#multiple	89.49% <100%> (-0.01%)	⬇️
#single	40.84% <100%> (-0.12%)	⬇️

Impacted Files	Coverage Δ
pandas/io/excel.py	90.09% <100%> (-0.04%)	⬇️
pandas/io/gbq.py	25% <0%> (-58.34%)	⬇️
pandas/core/frame.py	97.68% <0%> (-0.11%)	⬇️
pandas/core/indexes/datetimes.py	95.62% <0%> (-0.1%)	⬇️

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[jreback]

thanks!