[github-actions] do not delete artifacts if coverage upload fails (#7678)

Coverage upload can fail intermittently for various reasons. Do not
delete coverage artifacts if upload fails to avoid needing to re-run
the entire workflow.
diff --git a/.github/workflows/otbr.yml b/.github/workflows/otbr.yml
index 1b13aaa..e1c87b8 100644
--- a/.github/workflows/otbr.yml
+++ b/.github/workflows/otbr.yml
@@ -222,7 +222,6 @@
 
   delete-coverage-artifacts:
     needs: upload-coverage
-    if: always()
     runs-on: ubuntu-20.04
     steps:
     - uses: geekyeggo/delete-artifact@1-glob-support
diff --git a/.github/workflows/posix.yml b/.github/workflows/posix.yml
index 9603de6..abe6f0b 100644
--- a/.github/workflows/posix.yml
+++ b/.github/workflows/posix.yml
@@ -300,7 +300,6 @@
 
   delete-coverage-artifacts:
     needs: upload-coverage
-    if: always()
     runs-on: ubuntu-20.04
     steps:
     - uses: geekyeggo/delete-artifact@1-glob-support
diff --git a/.github/workflows/simulation-1.1.yml b/.github/workflows/simulation-1.1.yml
index 4fcc328..a16bf12 100644
--- a/.github/workflows/simulation-1.1.yml
+++ b/.github/workflows/simulation-1.1.yml
@@ -379,7 +379,6 @@
 
   delete-coverage-artifacts:
     needs: upload-coverage
-    if: always()
     runs-on: ubuntu-20.04
     steps:
     - uses: geekyeggo/delete-artifact@1-glob-support
diff --git a/.github/workflows/simulation-1.2.yml b/.github/workflows/simulation-1.2.yml
index f9673fc..f8bc267 100644
--- a/.github/workflows/simulation-1.2.yml
+++ b/.github/workflows/simulation-1.2.yml
@@ -330,7 +330,6 @@
 
   delete-coverage-artifacts:
     needs: upload-coverage
-    if: always()
     runs-on: ubuntu-20.04
     steps:
     - uses: geekyeggo/delete-artifact@1-glob-support
diff --git a/.github/workflows/toranj.yml b/.github/workflows/toranj.yml
index e8e083c..46f9520 100644
--- a/.github/workflows/toranj.yml
+++ b/.github/workflows/toranj.yml
@@ -146,7 +146,6 @@
 
   delete-coverage-artifacts:
     needs: upload-coverage
-    if: always()
     runs-on: ubuntu-20.04
     steps:
     - uses: geekyeggo/delete-artifact@1-glob-support