zlog: Replace usages of env_logger in tests with zlog (#31436)

Also fixes:
https://github.com/zed-industries/zed/pull/31400#issuecomment-2908165249

Release Notes:

- N/A *or* Added/Fixed/Improved ...

crates/git_ui/Cargo.toml

@@ -65,7 +65,6 @@ windows.workspace = true
 
 [dev-dependencies]
 ctor.workspace = true
-env_logger.workspace = true
 editor = { workspace = true, features = ["test-support"] }
 gpui = { workspace = true, features = ["test-support"] }
 pretty_assertions.workspace = true
@@ -73,3 +72,4 @@ project = { workspace = true, features = ["test-support"] }
 settings = { workspace = true, features = ["test-support"] }
 unindent.workspace = true
 workspace = { workspace = true, features = ["test-support"] }
+zlog.workspace = true