fix(webkitgtk): drop vestigial gstreamer-plugins-bad BR

[christopherco]

gstreamer1-plugins-bad-free is not shipped in AZL, so the hard
BuildRequires on pkgconfig(gstreamer-plugins-bad-1.0) caused dnf
builddep to fail during chroot init. The BR is vestigial in the
upstream Fedora spec: under default cmake options the WebKitGTK 2.50
sources do not #include any gst-plugins-bad headers (gst-bad headers
are only reached via GSTREAMER_MPEGTS / GSTREAMER_WEBRTC / LIBWEBRTC,
all of which default OFF for the GTK port). Removing the BR alone
unblocks the build without changing any runtime feature surface.

Fixes: AB#20292

[Copilot]

Pull request overview

Removes an unnecessary pkgconfig(gstreamer-plugins-bad-1.0) BuildRequires from the WebKitGTK component to unblock dnf builddep/chroot initialization on Azure Linux, where gstreamer1-plugins-bad-free (and thus its pkgconfig() provider) is not shipped.

Changes:

• Dropped the pkgconfig(gstreamer-plugins-bad-1.0) BuildRequires from the rendered WebKitGTK spec.
• Added a corresponding spec-remove-tag overlay in webkitgtk.comp.toml documenting why the dependency is vestigial under default CMake options.
• Updated the component lock input fingerprint and the rendered spec’s rpmautospec changelog/release.

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated no comments.

File	Description
specs/w/webkitgtk/webkitgtk.spec	Removes the gstreamer-plugins-bad BuildRequires and updates rpmautospec release/changelog accordingly.
locks/webkitgtk.lock	Updates input-fingerprint to reflect the component definition change.
base/comps/webkitgtk/webkitgtk.comp.toml	Adds an overlay to remove the vestigial gstreamer-plugins-bad BuildRequires with supporting rationale.