ci: don't output code coverage table in logs (#5813)

Problem: c8 was not given a reporter, therefore it defaulted to `text`
which is the terminal.
Solution: Set it to `lcov`, which is what we have been using previously.

Note: More work may be needed on the .c8rc.json files. We might not need
the one for core/ anymore. They may not be configured in the optimal
way. Is it behaving how we want it to?

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Author: hayemaxi

packages/toolkit/.c8rc.json

@@ -0,0 +1,6 @@
+{
+    "report-dir": "../../coverage/toolkit",
+    "reporter": ["lcov"],
+    "all": true,
+    "exclude": ["**/test*/**", "**/node_modules/**"]
+}