PR Build Workflow - Ensure tests run on all specified Node versions (#14)

*Issue #, if available:*
Not seeing tests run in the GH workflow:

https://github.com/aws-observability/aws-otel-js-instrumentation/actions/runs/10322310931/job/28577248584

*Description of changes:*
Update workflow to run unit tests for all Node versions

*Testing:*

https://github.com/aws-observability/aws-otel-js-instrumentation/actions/runs/10322590525/job/28578137898?pr=14

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Author: jj22ee

.github/workflows/pr-build.yml

@@ -16,6 +16,9 @@ jobs:
       fail-fast: false # ensures the entire test matrix is run, even if one permutation fails
       matrix:
         node: ["14", "16", "18", "20", "22"]
+        include:
+          - node: 18
+            code-coverage: true
     env:
       NPM_CONFIG_UNSAFE_PERM: true
     steps:
@@ -36,7 +39,6 @@ jobs:
       - name: Compile all NPM projects
         run: npm run compile
       - name: Unit tests (Full)
-        if: matrix.code-coverage
         run: npm run test
       - name: Report Coverage
         if: ${{ matrix.code-coverage && !cancelled()}}