Re-enable system ffmpeg

Description:

245e8526 added the comment: #[ffmpeg]=ffmpeg # YouTube playback stopped working in Chromium 120. However, reason is lacking.

It caused since ffmpeg's internal opus codec was not allowed_decoders (see url below). It should be commented in PKGBUILD.

Patch for ffmpeg is needed to fix the issue instead of leaving comment. See ffmpeg#17 (closed)

Additional info:

• package version: chromium 135.0.7049.84-1
• link to bug report: https://gitlab.alpinelinux.org/alpine/aports/-/issues/15585

Step to reproduce:

Sorry, I can't get resources to build chromium to test. See ffmpeg#17 (closed)