[CI] Do not double checkout macios-adr to keep the credentials. (#21807)

Doing a second checkout is error prone. One of the reason is that there
is no guarantee that any of our other scripts is not going to remove a
random temp directory (actually, the API diff make does remove it).

If the checkout directory is removed, the post checkout action from VSTS
will fail with something of the kind:

```
[error]An error occurred trying to start process '/usr/local/bin/git'
with working directory
'/Users/builder/azdo/_work/22/a/change-detection/tmp/src/macios-adr'. No
such file or directory
```

The reset script was doing the right thing by setting the http extra headers but it had a typo in the variable name.

mk/xamarin-reset.sh

@@ -39,10 +39,10 @@ if test -d "$DEPENDENCY_PATH"; then
 	fi
 
 else
-	echo "*** [$DEPENDENCY_NAME] git $DEPENDENCY_AUTH clone $DEPENDENCY_MODULE --recursive $DEPENDENCY_DIRECTORY -b $DEPENDENCY_BRANCH --origin $DEPENDENCY_REMOTE"
+	echo "*** [$DEPENDENCY_NAME] git" "${DEPENDENCY_AUTH[@]}" "clone $DEPENDENCY_MODULE --recursive $DEPENDENCY_DIRECTORY -b $DEPENDENCY_BRANCH --origin $DEPENDENCY_REMOTE"
 	mkdir -p "$(dirname "$DEPENDENCY_PATH")"
 	cd "$(dirname "$DEPENDENCY_PATH")"
-	git $DEPENDANCY_AUTH clone "$DEPENDENCY_MODULE" --recursive "$DEPENDENCY_DIRECTORY" -b "$DEPENDENCY_BRANCH" --origin "$DEPENDENCY_REMOTE"
+	git "$DEPENDENCY_AUTH" "$DEPENDENCY_MODULE" --recursive "$DEPENDENCY_DIRECTORY" -b "$DEPENDENCY_BRANCH" --origin "$DEPENDENCY_REMOTE"
 	cd "$DEPENDENCY_DIRECTORY"
 fi
 

tools/devops/automation/templates/build/api-diff-build-and-detect.yml

@@ -35,15 +35,6 @@ parameters:
 # build the source code (build.yml) and detect changes (the nested api-diff.yml)
 steps:
 
-# The following checkout(s) are needed due in order to get the proper set of credentials stored in the git config.
-# Without this, then when the `make reset` command is run, any modules that aren't configured already as submodules
-# will be cloned again. This is fine for all GitHub repos, but falls over for AzDo repos.
-- checkout: macios-adr-tmp
-  clean: true
-  persistCredentials: true
-  fetchTags: false
-  path: a/change-detection/tmp/src/macios-adr # Path is rooted from $(Pipeline.Workspace) e.g./Users/builder/azdo/_work/18
-
 - template: build.yml
   parameters:
     isPR: ${{ parameters.isPR }}