git config fails intermittently due to gitconfig lock

The script task that sets up gitconfig user and email properties fails occasionally due to parallel execution of the two git commands. The parallelism is due (I think) to a single `&` being used. If you use a double `&&` then this should solve the problem.

The problem source code is [here](https://github.com/Azure/arc-cicd-demo-src/blob/fd1099fad70205a46c4df0e75cc19555a7beaeb7/.pipelines/genmanifest-createpr-template.yaml#L23)

Open .pipelines/genmanifest-createpr-template.yaml at line 23 and inspect the gitconfig setup task. Verify that the user and email commands execute sequentially, then rerun the task repeatedly under parallel execution conditions; it is done when the intermittent gitconfig lock failure no longer occurs.

Written by the indexing model from the issue text.