ci: build native lib in the Coverage job too

The Coverage Report job runs 'mvn -P jacoco test' on core but had no native
build step, so after dropping the committed binaries it failed to load
libquestdb.so (NoClassDefFound in io.questdb.client.std.*). Add the
build_native.yaml template before the coverage test run, matching the
BuildAndTest job. The job runs on Linux, so it compiles libquestdb.so.

Author: bluestreak01

ci/run_tests_pipeline.yaml

@@ -150,6 +150,9 @@ stages:
                 maven | "$(Agent.OS)"
               path: $(HOME)/.m2/repository
             displayName: "Cache Maven repository"
+          # Native binaries are no longer committed; compile libquestdb.so on the
+          # runner so the coverage test run can load it (same as BuildAndTest).
+          - template: build_native.yaml
           - task: Maven@3
             displayName: "Run tests with coverage"
             inputs: