Remove LcovMerger from tools/test:embedded_tools.

 `CoverageOutputGenerator` is actually embedded into `bazel_tools` through [//tools:embedded_tools_srcs](https://github.com/bazelbuild/bazel/blob/master/tools/BUILD#L61).

The referenced changed in this PR is useless so I just deleted it.

Closes #7412.

PiperOrigin-RevId: 233917671
diff --git a/tools/test/BUILD b/tools/test/BUILD
index 81253c1..735e2fb 100644
--- a/tools/test/BUILD
+++ b/tools/test/BUILD
@@ -121,7 +121,7 @@
         "generate-xml.sh",
         "collect_coverage.sh",
         "collect_cc_coverage.sh",
-    ] + glob(["LcovMerger/**"]) + select({
+    ] + select({
         "@bazel_tools//src/conditions:windows": [
             "tw",
             "xml",