Fast-abort body size limit loses original error and may hang consumers

[VikramAditya33]

When processDecompressedChunk hits maxBodySize in fastAbort mode, the stream is never explicitly destroyed. It relies on uwsRes.close() eventually triggering the _onAbort callback, which:

1. Overwrites the original 'Body size limit exceeded' error with 'Connection aborted'
2. May leave awaiting consumers hanging briefly until the abort callback fires

Expected Behavior

• req.buffer() / req.json() / req.text() should reject with Error: Body size limit exceeded even in fastAbort mode
• The stream should be destroyed immediately with the correct error

Actual Behavior

• The original error is lost because _onAbort unconditionally sets this.abortError = new Error('Connection aborted')
• In test mocks (where close() does not trigger onAborted), the promise hangs forever

Proposed Fix

1. In the else (fast-abort) branch, explicitly call this.destroy(this.abortError) so the error is preserved and consumers are unblocked immediately
2. In the _onAbort callback, only set this.abortError if it isn't already set:

if (!this.abortError) {
  this.abortError = new Error('Connection aborted');
}