Revert "Disable PipeWire on Chromecast builds."

This reverts commit cc8c07895df8b34ad339b457f07a2e3724215d79.

Reason for revert: Breaks cast linux tests (https://ci.chromium.org/p/chromium/builders/ci/Cast%20Linux/93159)

Original change's description:
> Disable PipeWire on Chromecast builds.
> 
> For various reasons is_desktop_linux is true on Chromecast builds though
> arguably it should not be. This means that the detection logic previously
> used is incorrect for Chromecast builds. Since Chromecast needs to
> start enabling use_sysroot, this logic needs to explicitly exclude
> is_chromecast.
> 
> Bug: b/154635846
> Change-Id: I6ced6f7e4c78f9d8d7055018e68090883b9e21bd
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/174620
> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#31205}

TBR=mbonadei@webrtc.org,kwiberg@webrtc.org,tommi@webrtc.org,stefan@webrtc.org,juberti@webrtc.org,mflodman@webrtc.org,eliribble@google.com

Change-Id: Ibe8837fa4b845fe56d4d4ff63ffb38addfb58905
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: b/154635846
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/174827
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31221}
diff --git a/webrtc.gni b/webrtc.gni
index 21fe0ba..9750d4d 100644
--- a/webrtc.gni
+++ b/webrtc.gni
@@ -115,7 +115,7 @@
   # By default it's only enabled on desktop Linux (excludes ChromeOS) and
   # only when using the sysroot as PipeWire is not available in older and
   # supported Ubuntu and Debian distributions.
-  rtc_use_pipewire = is_desktop_linux && use_sysroot && !is_chromecast
+  rtc_use_pipewire = is_desktop_linux && use_sysroot
 
   # Set this to link PipeWire directly instead of using the dlopen.
   rtc_link_pipewire = false