Remove deprecated filter http_api_transports

[rebeccahum]

Description

Deprecated in https://core.trac.wordpress.org/changeset/56723.

Looks like the filter no longer fires since uploads now go directly through the Requests library: https://github.com/WordPress/WordPress/blob/915f28e18ed883cd706545cefd16b4d19b841c47/wp-includes/Requests/src/Requests.php#L225

Changelog Description

Remove deprecated filter http_api_transports

Removes filter http_api_transports that will be deprecated in WP 6.4

Pre-review checklist

Please make sure the items below have been covered before requesting a review:

• This change works and has been tested locally (or has an appropriate fallback).
• This change works and has been tested on a Go sandbox.
• This change has relevant unit tests (if applicable).
• This change uses a rollout method to ease with deployment (if applicable - especially for large scale actions that require writes).
• This change has relevant documentation additions / updates (if applicable).
• I've created a changelog description that aligns with the provided examples.

Pre-deploy checklist

• VIP staff: Ensure any alerts added/updated conform to internal standards (see internal documentation).

Steps to Test

[codecov]

Codecov Report

Merging #4962 (da97998) into develop (1f2749d) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@              Coverage Diff              @@
##             develop    #4962      +/-   ##
=============================================
- Coverage      29.20%   29.19%   -0.02%     
+ Complexity      4746     4745       -1     
=============================================
  Files            278      278              
  Lines          20903    20899       -4     
=============================================
- Hits            6105     6101       -4     
  Misses         14798    14798              

Files	Coverage Δ
files/class-curl-streamer.php	55.00% <ø> (-7.50%)	⬇️