Cherry-pick #19131 to 7.x: [filebeat][netflow] Support up to 7 bytepad for Netflow IPFIX template

[marc-gr]

Cherry-pick of PR #19131 to 7.x branch. Original message:

What does this PR do?

Fixes netflow v9 decoder to support up to 7 bytes of padding for IPFIX templates.

Why is it important?

Previously was failing to process packets with more than 3 bytes of padding.

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

Fixes #18098

[elasticmachine]

Pinging @elastic/siem (Team:SIEM)

[elasticmachine]

💚 Build Succeeded

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Build stats

• Build Cause: [Pull request #19191 opened]

• Start Time: 2020-06-15T10:13:26.181+0000

• Duration: 50 min 34 sec

Test stats 🧪

Test	Results
Failed	0
Passed	1722
Skipped	255
Total	1977

Steps errors

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• Name: Report to Codecov

  • Description: curl -sSLo codecov https://codecov.io/bash for i in auditbeat filebeat heartbeat libbeat metricbeat packetbeat winlogbeat journalbeat do FILE="${i}/build/coverage/full.cov" if [ -f "${FILE}" ]; then bash codecov -f "${FILE}" fi done

  • Duration: 2 min 22 sec

  • Start Time: 2020-06-15T11:00:12.410+0000

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