[202305] Checkout correct branch from sonic-mgmt-common and sonic-sws…

…s-common during pipeline build (#128)

#### Why I did it

Pipeline is always fetching latest of sonic-mgmt-common and sonic-swss-common repos for its builds. They must be use source code from 202305 branch

#### How I did it

Checkout latest from `$(System.PullRequest.TargetBranch)` during PR builds and from `$(Build.SourceBranchName)` during manual builds.

Known issue: other pipeline artefacts are still being downloaded from master branch. Not a blocker as of now.

#### How to verify it

Pipeline build

.github/workflows/semgrep.yml

@@ -0,0 +1,22 @@
+name: Semgrep
+
+on:
+  pull_request: {}
+  push:
+    branches:
+      - master
+      - '201[7-9][0-1][0-9]'
+      - '202[0-9][0-1][0-9]'
+
+jobs:
+  semgrep:
+    if: github.repository_owner == 'sonic-net'
+    name: Semgrep
+    runs-on: ubuntu-latest
+    container:
+      image: returntocorp/semgrep
+    steps:
+      - uses: actions/checkout@v3
+      - run: semgrep ci
+        env:
+           SEMGREP_RULES: p/default

azure-pipelines.yml

@@ -17,16 +17,25 @@ pr:
     - 202???
     - 201???
 
+variables:
+  - name: BUILD_BRANCH
+    ${{ if eq(variables['Build.Reason'], 'PullRequest') }}:
+      value: $(System.PullRequest.TargetBranch)
+    ${{ else }}:
+      value: $(Build.SourceBranchName)
+
 resources:
   repositories:
   - repository: sonic-mgmt-common
     type: github
     name: sonic-net/sonic-mgmt-common
     endpoint: sonic-net
+    ref: refs/heads/$(BUILD_BRANCH)
   - repository: sonic-swss-common
     type: github
     name: sonic-net/sonic-swss-common
     endpoint: sonic-net
+    ref: refs/heads/$(BUILD_BRANCH)
 
 stages:
 - stage: Build
@@ -72,16 +81,6 @@ stages:
         runBranch: 'refs/heads/master'
       displayName: "Download sonic buildimage"
 
-    - task: DownloadPipelineArtifact@2
-      inputs:
-        source: specific
-        project: build
-        pipeline: 127
-        artifact: sonic-mgmt-common
-        runVersion: 'latestFromBranch'
-        runBranch: 'refs/heads/master'
-      displayName: "Download sonic-mgmt-common"
-
     - script: |
         # PYTEST
         sudo pip3 install -U pytest