Cherry-pick #22721 to 7.x: Drop pkt_dstaddr and pkt_srcaddr when equals to "-"

[ChrsMark]

Cherry-pick of PR #22721 to 7.x branch. Original message:

What does this PR do?

This PR is to fix parsing error for vpcflow fileset when aws.vpcflow.pkt_dstaddr or aws.vpcflow.pkt_srcaddr equals to -.

Error message:

failed to parse field [aws.vpcflow.pkt_srcaddr] of type [ip] in document with id '229a9b7009-000001896666'. Preview of field's value: '-'

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

Related issues

• Closes [filebeat][aws][vpcflow] mapping errors on logs with "NODATA" & "SKIPDATA" log_status #22716

[elasticmachine]

Pinging @elastic/integrations-platforms (Team:Platforms)

[elasticmachine]

💚 Build Succeeded

the below badges are clickable and redirect to their specific view in the CI or DOCS

Expand to view the summary

Build stats

• Build Cause: Pull request #22824 opened

• Start Time: 2020-12-01T15:34:44.241+0000

• Duration: 56 min 11 sec

Test stats 🧪

Test	Results
Failed	0
Passed	1970
Skipped	259
Total	2229

💚 Flaky test report

Tests succeeded.

Expand to view the summary

Test stats 🧪

Test	Results
Failed	0
Passed	1970
Skipped	259
Total	2229