Remove deprecated function send_request()

[AlinderS]

Removed code deprecated in 910791c more than a year ago.
Also removed tests and monkeypatched test functions in xmatch which were not doing anything.

[codecov]

Codecov Report

Merging #2583 (25c1f5a) into main (31842df) will decrease coverage by 0.03%.
The diff coverage is 100.00%.

❗ Current head 25c1f5a differs from pull request most recent head 855d19b. Consider uploading reports for the commit 855d19b to get more accurate results

@@            Coverage Diff             @@
##             main    #2583      +/-   ##
==========================================
- Coverage   64.08%   64.05%   -0.04%     
==========================================
  Files         131      131              
  Lines       16927    16907      -20     
==========================================
- Hits        10847    10829      -18     
+ Misses       6080     6078       -2     

Impacted Files	Coverage Δ
astroquery/utils/commons.py	75.14% <100.00%> (-1.58%)	⬇️

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[bsipocz]

This would need a changelog entry, otherwise looks all good (see examples for other removed functionality for the wording).

Thanks, @AlinderS!

[bsipocz]

Thanks @AlinderS!