Revert "OTel: Add empty Host Rule for custom services"

Revert submission 149558

Reason for revert: https://tribe29.slack.com/archives/C085MHGLPJ6/p1786458273376609

Reverted changes: /q/submissionid:149558

Change-Id: I7869e24c2a3c28f5b9c30b0e6dcbbf5e732b071f

Author: TimotheusBachinger

tests/system/singlesite/BUILD

@@ -48,7 +48,6 @@ py_library(
         "//:gpl+nonfree_repo": [
             "//non-free/packages/cmk-liveproxyd",
             "//non-free/packages/cmk-telemetry:plugins-custom-query",
-            "//non-free/packages/cmk-telemetry:plugins-custom-service",
             "//non-free/tests/testlib/system:metric_backend",
             "//non-free/tests/testlib/system:opentelemetry",
             "//non-free/tests/testlib/system/cloud",