* Fix regression in PluginHTTPStream where request body closed prematurely
When WriteHeader was called before reading the request body in inter-plugin
communication, the body would be closed prematurely due to defer r.Body.Close()
executing when the function returned (after starting the response goroutine).
This fix moves defer r.Body.Close() into the goroutine to ensure the request
body remains available until after the response is fully processed.
Added test case TestInterpluginPluginHTTPWithBodyAfterWriteHeader to verify
the fix and prevent future regressions.
* Fix resource leak by closing request body in all PluginHTTPStream error paths
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Co-authored-by: Christopher Speller <crspeller@gmail.com>