fix(fluent source, logstash source): Remove non-working tests (#9576)

PR #9540 added event processing metrics to TcpSource sources, which
includes the fluent and logstash sources. These sources are emitting the
requisite events, but the events and metrics are not reaching the test
recorder. This patch removes the tests from these two sources until we
determine what is breaking.

Signed-off-by: Bruce Guenter <bruce.guenter@datadoghq.com>