Add Processors to linux package

[fearful-symmetry]

What does this PR do?

This is a fix for #1296

So, because a handful of linux data streams are actually backed by the system module within metricbeat, they'll break the mapping, since they'll report event.module as system and not linux. This adds a processor to said data streams, so we can drop the event in ingest, and then the proper value is inserted in the mapping.

This is a (somewhat) temporary workaround, as eventually the metricsets will be migrated to linux.

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.

How to test this PR locally

• Pull down and build
• On a linux host, run the elastic stack, add the linux integration and enable the entropy, network_summary, service, socket and users data streams. Note: users and service won't work if you're running the agent from inside a docker container
• Make sure the agent is healthy and all the data streams are collecting data.

[elasticmachine]

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Build stats

• Start Time: 2021-07-09T23:20:24.537+0000

• Duration: 12 min 38 sec

• Commit: 2e7a832

Test stats 🧪

Test	Results
Failed	0
Passed	19
Skipped	0
Total	19

Trends 🧪

[dikshachauhan-qasource]

Hi @EricDavisX

cc @fearful-symmetry we have validated it on latest 7.14 snapshot build on cloud-staging and found merges available.

Build details:

BUILD 42541
COMMIT 325493c86b4f58c308a3eb1f8bcfe5994a54533a

• Enable all the data-events under Linux integration and install agent using the Linux integration policy.
• Now all the metrics for Linux integration v0.4.1 are getting generated on data streams tab.

Screenshot:

Thanks
QAS