refactor!: remove go-git backend (#39487)

Removes the go-git backend so every build uses the git CLI backend. Its
Windows performance advantage is gone, it lacks SHA-256 support, and it
breaks repositories on Windows.

The performance changes moved to
https://github.com/go-gitea/gitea/pull/39526.

Fixes https://github.com/go-gitea/gitea/issues/38359
Fixes https://github.com/go-gitea/gitea/issues/34694

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/setting/git.go

@@ -28,7 +28,6 @@ var Git = struct {
 	GCArgs                        []string `ini:"GC_ARGS" delim:" "`
 	EnableAutoGitWireProtocol     bool
 	PullRequestPushMessage        bool
-	LargeObjectThreshold          int64
 	DisableCoreProtectNTFS        bool
 	DisablePartialClone           bool
 	DiffRenameSimilarityThreshold string
@@ -49,7 +48,6 @@ var Git = struct {
 	GCArgs:                        []string{},
 	EnableAutoGitWireProtocol:     true,
 	PullRequestPushMessage:        true,
-	LargeObjectThreshold:          1024 * 1024,
 	DisablePartialClone:           false,
 	DiffRenameSimilarityThreshold: "50%",
 	Timeout: struct {