Revert "gi: support freeing GObject return type everything"

This reverts commit 02f3f43af184da97f22f08fe10450bf285f26293.
Revert "gstreamer: bind GstStaticPadTemplate"

This reverts commit 608255476d86ed5acf79a91d0ae80e6b6b6e1673.

Because GstStaticPadTempalte is bound by GI as a struct. Sorry!