Make OneLocBuild reuse existing PRs (#8095)

Documentation/OneLocBuild.md

@@ -164,6 +164,7 @@ The parameters that can be passed to the template are as follows:
 | `SourcesDirectory` | `$(Build.SourcesDirectory)` | This is the root directory for your repository source code. |
 | `CreatePr` | `true` | When set to `true`, instructs the OneLocBuild task to make a PR back to the source repository containing the localized files. |
 | `AutoCompletePr` | `false` | When set to `true`, instructs the OneLocBuild task to autocomplete the created PR. Requires permissions to bypass any checks on the main branch. |
+| `ReusePr` | `true` | When set to `true`, instructs the OneLocBuild task to update an existing PR (if one exists) rather than open a new one to reduce PR noise. |
 | `UseLfLineEndings` | `true` | When set to `true`, instructs the OneLocBuild task to use LF line endings during check-in rather than CRLF. |
 | `GitHubOrg` | `'dotnet'` | The GitHub organization to be used when making a PR (only used when using a mirrored repository). |
 | `MirrorRepo` | `''` | The name of the GitHub repository to make a PR to (only used when using a mirrored repository). |

eng/common/templates/job/onelocbuild.yml

@@ -12,6 +12,7 @@ parameters:
   SourcesDirectory: $(Build.SourcesDirectory)
   CreatePr: true
   AutoCompletePr: false
+  ReusePr: true
   UseLfLineEndings: true
   UseCheckedInLocProjectJson: false
   LanguageSet: VS_Main_Languages
@@ -64,6 +65,8 @@ jobs:
         ${{ if eq(parameters.CreatePr, true) }}:
           isAutoCompletePrSelected: ${{ parameters.AutoCompletePr }}
           isUseLfLineEndingsSelected: ${{ parameters.UseLfLineEndings }}
+          ${{ if eq(parameters.RepoType, 'gitHub') }}:
+            isShouldReusePrSelected: ${{ parameters.ReusePr }}
         packageSourceAuth: patAuth
         patVariable: ${{ parameters.CeapexPat }}
         ${{ if eq(parameters.RepoType, 'gitHub') }}: