ci: only run tests when go files are touched (#5097)

## Description

_Please add a description of the changes that this PR introduces and the files that
are the most critical to review._ 

Closes: #XXX

.github/workflows/coverage.yml

@@ -38,57 +38,101 @@ jobs:
     needs: split-test-files
     steps:
       - uses: actions/checkout@v2
+      - uses: technote-space/get-diff-action@v1
+        with:
+          SUFFIX_FILTER: |
+            .go
+            .mod
+            .sum
+          SET_ENV_NAME_INSERTIONS: 1
+          SET_ENV_NAME_LINES: 1
       - uses: actions/download-artifact@v2
         with:
           name: "${{ github.sha }}-aa"
+        if: "env.GIT_DIFF != ''"
       - name: test & coverage report creation
         run: |
           cat xaa.txt | xargs go test -mod=readonly -timeout 8m -race -coverprofile=coverage.txt -covermode=atomic
+        if: "env.GIT_DIFF != ''"
       - uses: codecov/codecov-action@v1.0.7
         with:
           file: ./coverage.txt
+        if: "env.GIT_DIFF != ''"
 
   test-coverage-part-2:
     runs-on: ubuntu-latest
     needs: split-test-files
     steps:
       - uses: actions/checkout@v2
+      - uses: technote-space/get-diff-action@v1
+        with:
+          SUFFIX_FILTER: |
+            .go
+            .mod
+            .sum
+          SET_ENV_NAME_INSERTIONS: 1
+          SET_ENV_NAME_LINES: 1
       - uses: actions/download-artifact@v2
         with:
           name: "${{ github.sha }}-ab"
+        if: "env.GIT_DIFF != ''"
       - name: test & coverage report creation
         run: |
           cat xab.txt | xargs go test -mod=readonly -timeout 5m -race -coverprofile=coverage.txt -covermode=atomic
+        if: "env.GIT_DIFF != ''"
       - uses: codecov/codecov-action@v1.0.7
         with:
           file: ./coverage.txt
+        if: "env.GIT_DIFF != ''"
 
   test-coverage-part-3:
     runs-on: ubuntu-latest
     needs: split-test-files
     steps:
       - uses: actions/checkout@v2
+      - uses: technote-space/get-diff-action@v1
+        with:
+          SUFFIX_FILTER: |
+            .go
+            .mod
+            .sum
+          SET_ENV_NAME_INSERTIONS: 1
+          SET_ENV_NAME_LINES: 1
       - uses: actions/download-artifact@v2
         with:
           name: "${{ github.sha }}-ac"
+        if: "env.GIT_DIFF != ''"
       - name: test & coverage report creation
         run: |
           cat xac.txt | xargs go test -mod=readonly -timeout 5m -race -coverprofile=coverage.txt -covermode=atomic
+        if: "env.GIT_DIFF != ''"
       - uses: codecov/codecov-action@v1.0.7
         with:
           file: ./coverage.txt
+        if: "env.GIT_DIFF != ''"
 
   test-coverage-part-4:
     runs-on: ubuntu-latest
     needs: split-test-files
     steps:
       - uses: actions/checkout@v2
+      - uses: technote-space/get-diff-action@v1
+        with:
+          SUFFIX_FILTER: |
+            .go
+            .mod
+            .sum
+          SET_ENV_NAME_INSERTIONS: 1
+          SET_ENV_NAME_LINES: 1
       - uses: actions/download-artifact@v2
         with:
           name: "${{ github.sha }}-ad"
+        if: "env.GIT_DIFF != ''"
       - name: test & coverage report creation
         run: |
           cat xad.txt | xargs go test -mod=readonly -timeout 5m -race -coverprofile=coverage.txt -covermode=atomic
+        if: "env.GIT_DIFF != ''"
       - uses: codecov/codecov-action@v1.0.7
         with:
           file: ./coverage.txt
+        if: "env.GIT_DIFF != ''"