Revert "git: Intercept signing prompt from GPG when committing" (#34306)

Reverts zed-industries/zed#34096

This introduced a regression, because the unlocked key can't benefit
from caching.

Release Notes:
- N/A

crates/proto/proto/git.proto

@@ -294,7 +294,7 @@ message Commit {
     optional string email = 5;
     string message = 6;
     optional CommitOptions options = 7;
-    optional uint64 askpass_id = 8;
+    reserved 8;
 
     message CommitOptions {
         bool amend = 1;