Using template dsccommunity will not correctly set the MainGitBranch in build.yml for DscTest key

### Problem description

When using the template _dsccommunity_ the build.yaml that is generated does not contain the key `MainGitBranch` under the key `DscTest`.

```yaml
DscTest:
MainGitBranch: main
```

### Verbose logs

```text
n/a
```

### How to reproduce

Generate a module using the template _dsccommunity_.

### Expected behavior

To have the key `MainGitBranch`.

### Current behavior

No key is added.

### Suggested solution

Update file template of build.yml to include the key when using template _dsccommunity_.

### Operating system the target node is running

```text
n/a
```

### PowerShell version and build the target node is running

```text
n/a
```

### Module version used

```text
0.112.0
```