[Edge Runtime] Supabase Edge Function break when returning a response before consuming the HTTP body (especially with file uploads - multipart/form-data)

# Bug report ## Describe the bug Supabase Edge Functions behave inconsistently when returning a response before the HTTP body has been consumed. If the body is not consumed (e.g. not calling `req.formData()`), requests sometimes succeed, sometimes hang, and sometimes fail with an SSL error. This suggests Supabase’s API Gateway / runtime requires the body to be consumed before responding, but this is not documented and leads to confusing failures. ## To Reproduce ### Working example (consuming HTTP body before returning) ```ts Deno.serve(async (req) => { if (req.method !== 'POST') { return new Response(null, { status: 405 }) } console.log('Received request') await req.formData() console.log('Form data processed') return new Response(null, { status: 204 }) }) ```` * Returns a 204 as expected. * Occasionally still returns an SSL error (especially after switching back from the failing version). ### Failing example (NOT consuming HTTP body) ```ts Deno.serve(async (req) => { if (req.method !== 'POST') { return new Response(null, { status: 405 }) } console.log('Received request') // Not parsing the form data here // await req.formData() // console.log('Form data processed') return new Response(null, { status: 204 }) }) ``` * Weird behavior: * Sometimes works (especially with smaller files). * Sometimes doesn’t return anything at all; logs only show `shutdown`. * Sometimes fails with an SSL error. ### SSL error output ``` * TLSv1.2 (IN), TLS header, Supplemental data (23): * TLSv1.3 (IN), TLS alert, bad record mac (532): * OpenSSL SSL_read: error:0A0003FC:SSL routines::sslv3 alert bad record mac, errno 0 * Failed receiving HTTP2 data * OpenSSL SSL_write: SSL_ERROR_ZERO_RETURN, errno 0 * Failed sending HTTP2 data * Connection #25 to host [project-id].supabase.co left intact ``` ## Expected behavior * The function should return a `204` regardless of whether the body is consumed. * If consuming the body is required, this should be do…