FrameProcessor: remove unnecessary push task

When we call `FrameProcessor.push_frame()` we end up calling
`FrameProcessor.queue_frame()` on the next or previous processor which already
uses the input queue and guarantees frame ordering. So, there's no need to have
a two queues next to each other.

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to **Pipecat** will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Performance
+
+- Remove unncessary push task in each `FrameProcessor`.
+
 ## [0.0.74] - 2025-07-03
 
 ### Added