feat(SCM): Turn merged github PR comments off by default

[mikejihbe]

No description provided.

[codecov]

❌ 1 Tests Failed:

Tests completed	Failed	Passed	Skipped
29678	1	29677	243

View the top 1 failed test(s) by shortest run time

tests.sentry.core.endpoints.test_organization_details.OrganizationUpdateTest::test_various_options

Stack Traces | 4.28s run time

#x1B[1m#x1B[.../core/endpoints/test_organization_details.py#x1B[0m:852: in test_various_options
    assert "to {}".format(data["githubPRBot"]) in log.data["githubPRBot"]
#x1B[1m#x1B[31mE   KeyError: 'githubPRBot'#x1B[0m

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