[Cassandra] Thread names with spaces can now be parsed.

[taku333]

What does this PR do?

If the thread name contains a single-byte space, parsing will fail due to notSpace.

[Service Thread]

INFO  [Service Thread] 2017-07-31 16:17:35,655 GCInspector.java:258 - ParNew GC in 210ms.  CMS Old Gen: 562659176 -> 612323584; Par Eden Space: 411959296 -> 0; Par Survivor Space: 49544256 -> 51445760

Reference URL, content is irrelevant.
https://stackoverflow.com/questions/45421130/cassandra-lots-of-gc-on-specific-nodes

Therefore , I was changed data(Equivalent to .*).

 _thread_name %{data:logger.thread_name}

https://docs.datadoghq.com/logs/log_configuration/parsing/?tab=matchers#matcher-and-filter

Motivation

Cassandra Integration was implemented, but some logs were not parsed.

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged