ci: codecov doesn't run in Github Actions

Problem:
Codecov doesn't run in Github Actions. This is because:
- The `github.ref == 'master'` condition is incorrect. We want the
  _target_ branch, not the source branch.
- The `|| github.event_name == 'pull_request'` condition was removed in
  034257e.

Solution:
Fix the condition. Note that `github.base_ref` is only defined for pull
requests, so we require `github.event_name == 'pull_request'`.

Author: justinmk3

.github/workflows/node.js.yml

@@ -84,7 +84,7 @@ jobs:
               env:
                   # Unset NODE_OPTIONS because of https://github.com/codecov/uploader/issues/475
                   NODE_OPTIONS: ''
-              if: ${{ github.repository == 'aws/aws-toolkit-vscode' && github.ref == 'master' }}
+              if: ${{ github.repository == 'aws/aws-toolkit-vscode' && github.event_name == 'pull_request' && github.base_ref == 'master' }}
               uses: codecov/codecov-action@v5
               with:
                   flags: macos-toolkit-unittests
@@ -95,7 +95,7 @@ jobs:
               env:
                   # Unset NODE_OPTIONS because of https://github.com/codecov/uploader/issues/475
                   NODE_OPTIONS: ''
-              if: ${{ github.repository == 'aws/aws-toolkit-vscode' && github.ref == 'master' }}
+              if: ${{ github.repository == 'aws/aws-toolkit-vscode' && github.event_name == 'pull_request' && github.base_ref == 'master' }}
               uses: codecov/codecov-action@v5
               with:
                   flags: macos-amazonq-unittests
@@ -154,7 +154,7 @@ jobs:
               env:
                   # Unset NODE_OPTIONS because of https://github.com/codecov/uploader/issues/475
                   NODE_OPTIONS: ''
-              if: ${{ github.repository == 'aws/aws-toolkit-vscode' && github.ref == 'master' }}
+              if: ${{ github.repository == 'aws/aws-toolkit-vscode' && github.event_name == 'pull_request' && github.base_ref == 'master' }}
               uses: codecov/codecov-action@v5
               with:
                   flags: windows-unittests